VSB - Technical University of Ostrava Faculty of Metallurgy and Materials Engineering
Department of Quality Management
DIPLOMA THESIS
Analysis of Car Clutch Pressure Plate Assembly
2018 BE. Tilson Daniel Kamudurai
Abstract
The diploma thesis namely “Analysis of the Car Clutch Pressure Plate Assembly Quality Characteristics” is a work conducted to improve the quality of the friction plate clutch assembly, produced at the Indian company, by reducing the defects. Friction plate clutch has pressure plate assembly which contains pressure disc, diaphragm spring, fork lifter and thrown out pilot bearings. In this study, the author mainly focuses on various defects in the car clutch pressure plate assembly, the causes of defects and their impact. In this study, an analytical type of research was used to analyse the defects on pressure plate clutch assembly by collecting data, in order to determine the frequency of defects of various types. Further the author has used secondary data for the research study. The secondary data was gathered from the quality department at the mentioned Indian producer of the car clutches. These defect data are analysed by using quality control tools such as trend analysis, statistical hypothesis testing, Pareto analysis, control charts, cause and effect diagram. From the findings suitable suggestions to the company to overcome the defects of existing clutch assembly, to improve the customer satisfaction and also to improve business in future grounds are given.
Key words: pressure plate clutch assembly, defects, Pareto chart, testing statistical hypothesis, root cause
Abstrakt
Cílem diplomové práce s názvem “Analýza charakteristik kvality přítlačného kotouče automobilové spojky” je přispět ke zvýšení kvality třecí spojky u indického výrobce, a to konkrétně redukcí výskytu vad na přítlačném kotouči. Autor práce se zabývá také vlivem těchto vad na kvalitu spojky a analýzou příčin těchto vad. Analytická část práce je založena na sběru dat o výskytu různých vad na přítlačném kotouči. Data byla autorem práce získána ze záznamů útvaru kvality daného indického výrobce spojek. Tato data byla dále analyzována pomocí nástrojů a metod, jako jsou analýza trendů, testování statistických hypotéz, Paretova analýza, regulační diagram, diagram příčin a následků. Na základě zjištění byla formulována doporučení, jak snížit výskyt vad vyráběných spojek a jak zvýšit spokojenost zákazníků a zlepšit ekonomické výsledky výrobce v budoucnu.
Klíčová slova: přítlačný kotouč spojky, vady, Paretův diagram, testování statistické hypotézy, kořenová příčina
CONTENTS
INTRODUCTION ... 9
1. RESEARCH METHODOLOGY ... 11
1.1 Type of research design ... 11
1.2 Data collection ... 11
1.3 Data processing ... 11
1.4 Data coding, formatting and storing... 11
1.5 Tools for analysis ... 11
1.5.1Trend analysis ... 12
1.5.2 Two sample Poisson rate test ... 12
1.5.3Pareto chart ... 13
1.5.4Control chart ... 15
1.5.5 Cause and effect diagram ... 18
1.6 Assumptions, constraints and limitations ... 20
2. CHARACTERIZATION OF THE COMPANY ... 21
2.1 Basic information about products in the company ... 22
2.2 Description of clutch ... 22
2.3 Operation of the clutch ... 24
2.4 Single plate clutch ... 25
2.4.1 Working of single plate clutch ... 29
3. MANUFACTURING PROCESS OF PRESSURE PLATE ... 30
3.1 Machining ... 30
3.2 Joining process overview ... 31
3.3 Inspection Process ... 32
3.4 Quality factors involved in the pressure plate clutch assembly failure detections: .. 33
3.3.1 Clamp Load ... 34
3.3.2 Clamp Wear ... 34
3.3.3 Bearing Load ... 35
3.3.4 Bearing Wear ... 35
3.3.5 Bearing Height ... 35
3.3.6 Parallelism ... 36
3.3.7 Fingers broken ... 36
3.3.8 Pressure plate Lift ... 37
3.3.9 Fouling... 37
3.3.10 Run out ... 37
3.3.11 Unbalanced mass (UBM) ... 38
4. DATA ANALYSIS AND INTERPRETATION... 40
4.1 Trend analysis ... 40
4.2 Two sample Poisson rate test ... 41
4.3 Pareto analysis ... 44
4.3.1 Analysis of pressure plate clutch assembly - May 2016 [A1.1] ... 45
4.3.2 Analysis of pressure plate clutch assembly - June 2016 [A1.1] ... 46
4.3.3 Analysis of pressure plate clutch assembly - July 2016 [A1.1] ... 47
4.3.4 Analysis of pressure plate clutch Assembly - August 2016 ... 48
4.3.5 Analysis of pressure plate clutch assembly - September 2016 ... 49
4.3.6 Analysis of pressure plate clutch assembly - October 2016 ... 50
4.3.7 Analysis of pressure plate clutch assembly - November 2016 ... 51
4.3.8 Analysis of pressure plate clutch assembly - December 2016 ... 52
4.3.9 Analysis of pressure plate clutch assembly - January 2017 ... 53
4.3.10 Analysis of pressure plate clutch assembly - February 2017 ... 54
4.3.11 Analysis of pressure plate clutch assembly - March 2017 ... 55
4.3.12 Analysis of pressure plate clutch assembly - April 2017 ... 56
4.3.13 Analysis of pressure plate clutch assembly for 2016/2017 ... 58
4.4 Control charts ... 62
4.4.1 Analysis of pressure plate clutch assembly – May 2016 ... 62
4.4.2 Analysis of pressure plate clutch assembly – June 2016 ... 64
4.4.3 Analysis of pressure plate clutch assembly – July 2016 ... 66
4.4.4 Analysis of pressure plate clutch assembly – August 2016 ... 68
4.4.5 Analysis of pressure plate clutch assembly – September 2016 ... 71
4.4.6 Analysis of pressure plate clutch assembly – October 2016 ... 72
4.4.7 Analysis of pressure plate clutch assembly – November 2016 ... 75
4.4.8 Analysis of pressure plate clutch assembly – December 2016 ... 78
4.4.9 Analysis of pressure plate clutch assembly – January 2017 ... 79
4.4.10 Analysis of pressure plate clutch assembly – February 2017 ... 81
4.4.11 Analysis of pressure plate clutch assembly – March 2017 ... 82
4.4.12 Analysis of pressure plate clutch assembly – April 2017 ... 84
4.5 Cause and Effect Diagram ... 85
5. CONCLUSIONS ... 89
5.1 Findings ... 89
5.2 Suggestions ... 89
5.3 Conclusion ... 90
5.4 Direction for future research ... 90
REFERENCES ... 91
List of used abbreviations and symbols
UBM Unbalanced Mass
PP lift less Pressure plate lift
𝐻𝑜 Null hypothesis (𝐻𝑜)
𝐻1 Alternate hypothesis
LCV Light commercial vehicles
HCV Heavy commercial vehicles
OEM Original equipment manufacturer
R&D Research and development
ISO International Organization for
Standardization
QS Quality standards
TS Technical specification
DMF Dual mass flywheel
CMM Co-ordinate measuring machine
OHSAS Occupational Health and Safety Assessment
Series
TQM Total quality management
RPM Revolutions per minute
KN Kilo newton
N Newton
9 INTRODUCTION
The diploma thesis namely “Analysis of the Car Clutch Pressure Plate Assembly Quality Characteristics” is focused on the performance of the commercial vehicle clutch plate assembly. The existing clutch assembly system running in the vehicle has the frequent
complaints, which produces higher vehicle down time. Due to wear of the clutch during usage, the clutch doesn't interact fully when the pedal is discharged. When shifting gears, the clutch slips mostly during engine loads, like climbing hills or high vehicle speeds.
Clutch slips are known by increase in engine revolutions per minute while not increase in vehicle speed. The clutch doesn't disengage fully to permit smooth shift operations. Gear clashing is caused when the vehicle is idle or when shifting in and out of gears while the vehicle is moving which leads to clutch failure and also the other reasons behind clutch failure is due to excessive heat and by rattle noise which is noticed while the clutch engages or disengages.
Excessive heat produced between the flywheel, intermediate plate driven discs, pressure plate which will cause the metal to flow and also the material to be cracked. If this happens, the clutch will burst which may cause property injury, serious physical injury or death.
Hence to identify the various problems in the clutch pressure plate assembly the data from the Quality Department at the producer of the clutches were collected. In this study, an analytical type of research was used. Here we can use the secondary data for the analysis. The secondary was obtained from the company’s past records.
The objective of the project is to find the problems within the clutch assembly and recommend a possible resolution to overcome the existing problems. In addition to that we are able to solve the issues within the existing product, we are able to satisfy the customers, eventually resulting in a stand for client retention, inviting new customers through your solutions and increase the profit rate of the firm.
The existing clutch assembly system running in the vehicle has the frequent complaints.
[1] Hence some of the possible problems identified in clutch pressure plate assembly are as follows:
➢ clamp load new less,
➢ clamp load wear less,
➢ bearing load new more,
➢ bearing load wear less,
➢ bearing height more,
➢ bearing height less,
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➢ parallelism more,
➢ finger broken,
➢ PP lifts less,
➢ fouling,
➢ run out,
➢ UBM.
The primary objective is to study and access the performance characteristics of clutch pressure plate assembly.
The objectives of the research are:
➢ to find various occurrences of defects in clutch assembly,
➢ to find out the root cause for the defects in clutch assembly,
➢ to take corrective measures to reduce the defects by using special quality control tools,
➢ to give better suggestions for the management to improve the design of clutch assembly used in the commercial vehicle.
The scope of the diploma thesis mainly deals with customer perceptions and their expectations towards service quality. The study also helps the company to understand their customers effectively in order retain them and also to frame strategies to attract new customers.
The analyses will help the organization to increase the profit rate of the firm and reduce the number of defects. Based on the research, the author proposes an appropriate solution / alternative to remove the cause of problem. Identifying the promising areas of enhancement and signifying improvement methods by new approaches to fulfill the customer and to improve the business.
The key deliverables of the study are [1]
➢ to improve the performance of the pressure plate clutch assembly,
➢ to give suitable. alternatives to remove the cause of problem,
➢ to improve the customer satisfaction.
11 1. RESEARCH METHODOLOGY
Research methodology is the method to collect information and data for the purpose of finding the root cause of the defects in the existing car clutch pressure plate assembly. This chapter deals with the procedures for data collection and analysis.
1.1 Type of research design
Research design is the basic frame work which gives guidelines for whole research methodology. In this diploma thesis, the author has used analytical research method.
The purpose of using an analytical research is to collect the existing facts about clutch characteristics that affect the pressure plate clutch assembly. Analytical research contains reviews and fact-finding. The importance of the analytical research is to analyse and evolve the existing facts collected through Secondary Data.
1.2 Data collection
Pressure plate assembly defects data are collected from the company past records for the period of 12 months from May 2016 till April 2017.
1.3 Data processing
Research is conducted for acquiring information. Raw data as such does not provide information. Further analyses need to be done to crunch information out of data. Data analysis involves application of statistical quality control techniques for reducing accumulated data to a manageable size leading to summaries. Data processing consists of data collection, data coding, formatting and storing.
1.4 Data coding, formatting and storing
Data is collected in the form of softcopy; i.e. the company records in soft copy were collected and noted down manually on the computer using Microsoft Excel. Thus, all the data were collected and used for data analysis and interpretation.
1.5 Tools for analysis
Different type of analysis is carried out using the following tools in this research:
➢ trend analysis,
➢ two sample Poisson rate test,
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➢ Pareto chart,
➢ control chart,
➢ cause and effect diagram.
1.5.1 Trend analysis
Trend analysis is used to show the present and future movement of the process with respect to time series data. In the trend analysis data are compared over the period of time and it highlights the trend.
It is a method of analysis which allows the company or an organization to predict what can happen in the future. The use of trend analysis is to examine data over the time and it able to predict the future occurrences.
Analysis of trends may focus on:
• patterns of change in an indicator over time,
• comparing one-time period to another time period,
• making future projections.
1.5.2 Two sample Poisson rate test
The Poisson rate test is used to determine the rates of non-conformities for two different samples. The Poisson probability law shows us the probability distribution of the number of non-conformities in a particular interval of time.
This test can be used to determine whether the rates of nonconformities (defects) for two samples differ. [11]
The null and alternative hypotheses can be then specified as follows:
H0: λ1 - λ2 = 0
The difference between the nonconformities rates of two samples (λ1– λ2) is equaled to zero.
a) H1: λ1 - λ2 ≠ 0
The difference between the nonconformities rates of two samples (λ1– λ2) is not equal to zero.
b) H1: λ1 - λ2 > 0
The difference between the nonconformities rates of two samples (λ1– λ2) is greater than zero.
c) H1: λ1 - λ2 < 0
The difference between the nonconformities rates of two samples (λ1– λ2) is less than zero.
13 Notations:
𝜆1 = 𝑡𝑜𝑡𝑎𝑙 𝑛𝑜𝑛𝑐𝑜𝑛𝑓𝑜𝑟𝑚𝑖𝑡𝑖𝑒𝑠 𝑖𝑛 𝑠𝑎𝑚𝑝𝑙𝑒 1 𝑠𝑖𝑧𝑒 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 1
𝜆2 =𝑡𝑜𝑡𝑎𝑙 𝑛𝑜𝑛𝑐𝑜𝑛𝑓𝑜𝑟𝑚𝑖𝑡𝑖𝑒𝑠 𝑖𝑛 𝑠𝑎𝑚𝑝𝑙𝑒 2 𝑠𝑖𝑧𝑒 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 2
Using software Minitab, the interpretation is as follows. To determine whether the difference between the rates of non-conformities is statistically significant, we compare the p- value to the significance level. Usually, a significance level (denoted as α) of 0.05 is applied. A significance level of 0.05 indicates a 5% risk of concluding that a difference exists when there is no actual difference. [12]
If the p-value is less than or equal to the significance level α, the decision is to reject the null hypothesis - the difference between the rates is statistically significant and we can conclude that nonconformities rates are different.
If the p-value is greater than the significance level α, the decision is not to reject the null hypothesis - the difference between the rates is not statistically significant. We have not enough evidence to conclude that the defect rates are different.
1.5.3 Pareto chart
A Pareto chart, derived from the scientist Vilfredo Pareto, is a type of chart where discrete values are represented in descending order by using bars, and the cumulative values are represented using line. Pareto analysis is the act of using principle 80/20 and which is one of the first seven quality tools. It is a unique type of Bar Chart to show the results from Check Sheet, Prioritization matrix and voting.
The Pareto chart is used to point out the important things for which it has to be focused and to differentiate the vital few and trivial many. It can be used to improve a process and to show a change in the measured item and to sort a set of measurements. Pareto chart is widely used to show the priority of set of numeric measurements.
Understanding the Pareto chart is simple when a set of recurring problems occur. It is believed that the same set of problems will occur at the same number of times in one period.
some problems may occur far than the rest. When there are some unusual distributions occur, we can find out the vital few causes from the trivial many causes. The number of items measured are sorted into order.
The Pareto chart is mainly used for the decision-making process where in a stable process the order of the bars may be constant. When there is a change in the bars with proper
(1) (2)
14
measurements it will indicate an unstable process. Further down if there are any changes made to the process or any improvements made the order of the bars will change where when they are maintained the new chart will be stable. The bar type Pareto chart is more feasible which allows us to make an easy selection of items for further improvements. [13]
The Pareto charts have two axes, horizontal axis and vertical axis, where vertical axis is used to refer a frequency of detection and it is also used to represent the cost and other unit of measurement. The decreasing order for the chart is the cumulative function or indication of the concave unit.
The importance of the Pareto analysis is to find out most important factor or parameters in terms of quality it is usually known as common defects, as the results the highest possible occurrence of these defect is the most frequent issue or reason for the customer complaints.
Wilkinson [13] drives a procedure for statically based acceptance limits for each bar indications in the Pareto analysis.
The Pareto chart is a kind of visualization whereas bars and line graph. Here the separate values are represented in descending order by using bars, and the cumulative values are represented using line. For example, the line begins from the top of the first bar and move towards the right. In the second bar the line shows the combined total of both the bars in percentage, showing a total of part of both the items out of the entire group of items. On the final bar the line’s overall value will be equal to 100% representing the cumulative percentage of all the bars. The chart is a description of the Pareto principle, roughly 80% of the defects come from 20% of the causes. This principle is named after an Italian Engineer Vilfredo Pareto.
The Pareto analysis derived from histogram shows the causes of a problem in the order from largest to smallest. We are able to specified the important causes among the huge factors.
This is used in quality control parameters where it can able to the identify the common causes of defects, the frequently occurring defects and most frequently the reason for customer complaints.
Pareto chart tells us a few things where the bars/columns shows the occurrence of an event likewise the line shows the cumulative percentage. We can also identify which characters have represented the most so that it allows us to focus on the most important categories which differentiates the vital few and the trivial many. The principle of Pareto is described as the 80- 20 rule where it gives an example that 80% of the problems are of 20% of its potential problem sources. [13]
15 1.5.4 Control chart
Control charts will be used to investigate common and special causes of variation in a repeating process. They show whether a process is in a state of statistical control and if any action is needed to bring the process in control. This chart is used for identifying special causes and common causes, where the special causes are noticed at first. [9]
The variation of the points between the control limits is due to "common causes" that influence the process. Any point which lies outside the control limits is because of special cause implying a shift in the process. If a process is influenced by common causes, then it is stable which is predictable. The main goal of the control chart is to identify the occurrence of special causes, that it should be removed to reduce the overall process variation. The special cause of variation is represented by the point outside the control limits which shows that something unusual has occurred. We have two types of control charts: variable and the attributes charts.
Attributes control charts are similar in structure to variables control charts, except that they plot statistics from count data rather than measurement data. For instance, products may be compared against a standard and classified as either being defective or not. Products may also be classified by their number of defects. [10]
In this diploma thesis the control charts are done based on the software Minitab. As the diploma thesis is focused for the analysis of defects control charts for non-conformities have been selected and applied.
The control charts for defects are classified below:
➢ C Chart, which charts the number of defects (non-conformities) in each subgroup. A C chart is used when the subgroup size is constant.
➢ U chart, which charts the number of defects per unit sampled in each subgroup. A U chart is used when the subgroup size varies.
➢ Laney U' Chart, which charts the number of defects per unit sampled in each subgroup, while correcting for overdispersion where overdispersion exists when data exhibit more variation than it would be expected based on a Poisson distribution (for defects) or underdispersion where underdispersion exists when data exhibit less variation than it would be expected based on a Poisson distribution (for defects).
Data plotted, the control limits and centre line for U chart are computed by the following formulas. [12] The average count of non-conformities per unit of a criteria of interest in sample of items (data plotted) can be computed as follows: [19]
𝑢𝑗 = 𝑥𝑗
𝑛𝑗 (3)
16 for j=1,2,3…….m.
Centre line can be computed using the formula:
𝑢̅ = ∑𝑥𝑗
∑𝑛𝑗 for j=1,2,3…….m.
Upper control limit (UCL) and lower control limit (LCL) are computed as follows:
UCL = 𝑢̅ + 3√𝑛𝑢̅
𝑗
LCL = max (0,𝑢̅ − 3√𝑛𝑢̅
𝑗) Notation
𝑢𝑗= average count of non-conformities (defects) per unit, 𝑥𝑗 = number of non-conformities (defects) for subgroup, 𝑛𝑗 = size (number of units) of subgroup,
𝑢̅= centre line - average number of non-conformities (defects), m = number of subgroups included in the analysis.
The control limits in the U chart varies based on the sample size.
The Laney U' chart is similar to a traditional U chart. The Laney U' chart is useful in the following situations:
1. For large subgroups and if the data exhibit overdispersion.
Overdispersion can cause the points on a traditional U chart to appear to be out of control when it is not true. For the Laney U' chart, the definition of common cause variation includes not only the within-subgroup variation, but also the average variation between consecutive subgroups. If there is overdispersion, the control limits on a Laney U' chart are wider than those of a traditional U chart. The wider control limits mean that only important deviations in your process are identified as out of control.
2. If the data exhibit underdispersion.
Underdispersion, which can occur with subgroups of any size, is often caused by a lack of randomness. Underdispersion can result in control limits in traditional U chart that are too wide for the data. The Laney U' chart corrects for underdispersion by calculating narrower control limits. The calculations for the Laney U' chart include σ𝑧, which is an adjustment for overdispersion or under dispersion. A σ𝑧 value of 1 indicates that no adjustment is necessary and that the Laney U' chart is exactly the same as a traditional U chart. The
(4)
(5) (6)
17
plotted points represent the defect rate for each subgroup 𝑢𝑗: It is the same as the traditional U chart formula (3).
Center line is also computed in the same way as computed in the traditional U chart - formula (4).
To calculate the control limits in the Laney U’ chart each subgroup rate 𝑢𝑗 is converted to a z- score (𝑧𝑗):
𝑧𝑗 =
(𝑢𝑗− 𝑢̅)
𝑗
√𝑢̅/𝑛𝑗
Next, a moving range of length 2 is used to evaluate the variation in the z-scores and calculate Sigma Z (σ𝑧):
σ𝑧= 𝑀𝑅̅̅̅̅̅/1.128
where 1.128 is an unbiasing constant. Then the z- scores are transformed back into defect rates:
𝑢𝑗 = 𝑢̅ + σ𝑢𝑗∗ σ𝑧 The standard deviation of each plotted point is calculated as:
𝑠𝑑(𝑢𝑖) = 𝜎𝑢𝑗 ∗ σ𝑧 Control limits are calculated as:
UCL = 𝑢̅ + 3√𝑛𝑢̅
𝑗∗ σ𝑧 LCL = 𝑢̅ − 3√𝑛𝑢̅
𝑗 * σ𝑧
Notation
𝑥𝑗 = number of defectives in subgroup j 𝑛𝑗 = subgroup size for subgroup j σ𝑢𝑗 = 𝑠𝑞𝑟𝑡 (𝑢/ j)
𝑧𝑗 = z-score for subgroup j
𝑀𝑅̅̅̅̅̅ = average moving range of length 2 for the z-scores U chart diagnostic
U chart diagnostic is used to test the overdispersion or underdispersion in defects data.
Overdispersion shows an increased number of points outside the control limits.[8]
Underdispersion is caused when too few points are outside of the control limits. This diagnostic analysis is used to determine whether a traditional U chart or a Laney U' chart is more (7)
(9)
(10)
(11) (12) (8)
18
appropriate to show the number of defects per unit in the sample. If the test determines that the data exhibit overdispersion or underdispersion a Laney U' chart may more accurately distinguish between common cause variation and special cause variation.
At the U chart diagnostic firstly, a standard probability plot of the transformed counts is created (see an example on Fig. 1).
Fig. 1 U chart Diagnostic for Defects
Ratio of the observed variation to expected variation and 95% upper and conservative 95% lower confidence limits for this ratio are then calculated and decision about suitable. U chart is done:
➢ If the ratio is greater than the upper limit, the test determines that using a traditional U chart with the data may result in an elevated false alarm rate. A Laney U’ chart is recommended.
➢ If the ratio is less than lower limit, the test determines that using a traditional U chart with the data may result in a chart with control limits that are too wide. A Laney U’ chart is recommended.
1.5.5 Cause and effect diagram
The cause and effect diagram are the invention of Kaoru Ishikawa, who coined the quality management processes in the Kawasaki shipyard and this approach becomes one of the milestone for the modern management. The basic thought of the cause and effect diagram is to find out or explore the various root causes of the single problem. In the cause and effect diagram
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the various causes are analysed and list down as per the hierarchy. It majorly helps to find the root causes of the problems and help compare the relative different causes.
Cause and effect diagram is also called as fish bone diagram because the outline of the cause and effect structure give the resemblance of skeleton of fish or spine with bones structure.
Cause and effect is used for addressing a problem and select the major problem to conduct an investigation. When the main or the primary problem is identified the possible root causes are not clear where it can be found out working with a cross function team to have more knowledge of the problem causes and their relationship.
It is understood that the problems are not easy to be found at the first step. We can only address the symptoms but not the true causes of the identified problem. Identifying the causes will be an intermediate step which makes solution to be found easier and also to address the problem completely.
While observing the cause of a problem the most important causes which needs to be prioritized are rarely all known, where the effects individual causes are let alone on the problem and on one another. The cause and effect diagram is most commonly used within a brainstorming session, where the root cause of the actual problem may be a collective of known, possible causes and other suspected causes.
Root causes are the final chain of causes which do not hold any sub-causes. It is worth addressing the root causes. [13]
After interpretation of cause on various problems or defects, voting has been done to prioritize the most important defects.
Steps to execute the cause and effect diagram are as follows:
1. Define the problem and analyse the effect.
2. Perform the analysis and find the uncover possible causes through brainstorming.
3. Draw the effect box and centre line.
4. Stipulate the most important potential cause groups and attach the box to the centre line.
5. Classify the probable causes and categorize them in step 4. create new groups, if necessary.
6. Rank order the causes to identify most likely impact the problem.
7. Take necessary corrective action.
After computing the cause and effect diagram severity rating or also called as voting is given based on the man, methods, machine, measurement and material. The lowest rating is given as 1 and the highest is 5. This rating is based on the severity of the root causes and the total value of these rating are taken into account in order to prioritize which process has influenced the major root cause of the pressure plate clutch assembly.
20 1.6 Assumptions, constraints and limitations
➢ The study and analysis are done based on the inputs from the company records.
➢ The findings of the study are solely based on the information provided by the company.
➢ The accuracy of findings is limited by the accuracy of statistical tools used for the analysis.
21 2. CHARACTERIZATION OF THE COMPANY
The company was formed in 1967 for the manufacturing and marketing of clutch assemblies and service kits for Passenger Cars, LCVs, HCVs and Tractors. In addition to forging strong ties with major OEMs in the country. It enjoys a significant share of business in the aftermarket and state transport undertakings across India. These apart, the company also export its products. The auto component manufacturing companies of the Group have worked with practically every major OEM in the country, to bolster their import substitution requirements. Strong collaborations with international market leaders have influenced the technology advancements. These, combined with technological innovations and strong
initiatives on new product development, have contributed substantially to a strong equity in the after-markets as well, ably supported by vibrant national distribution networks. The Group's
overseas presence and distribution have over time, moved from strength to strength. [16]
The Group's Rand D facilities have focused on proactive product development and have cemented a strong base in the domestic and overseas markets. In fact, several of the Group Companies have obtained ISO, QS, TS and other international certifications for quality and environmental management systems. As a business philosophy, the Group companies maintain their leadership status by focusing on new generation technologies. A carefully calibrated strategy of the product-market matrix has enabled sharp focus on the product range, Rand D capabilities and new technologies, besides sales and distribution. These initiatives have enabled the Group to build a sound technology platform, with strong in-house capabilities.
The company has an extremely strong technology and manufacturing infrastructure.
Time and again, it has forged relationships with leading manufacturers from around the world, to cement partnerships and build on the technology quotient.
The Group has always subscribed to technology leadership at two levels: through organic knowledge that accrues out of a strong research base from within the organization and out of knowledge of the operational markets; and through strategic tie-ups to leverage strengths. This is why the research and development skills in the Group companies have contributed immensely through continuous product improvement and new product development, for both domestic and export markets. And not surprisingly, many of these facilities have been accorded due recognition by the Department of Scientific and Industrial Research, Government of India.
The quality is maintained and checked using the few control methods like
• push clutch control machine,
• 6 station indexing machine for assembly of clutch roller bearing with load measurement,
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• CMM (co-ordinate measuring machine),
• torsiograph control machine,
• release stroke control / disc control machine.
Quality standards in company
• ISO/TS 16949
• ISO 14001
• OHSAS 18001
• Q1 FORD
2.1 Basic information about products in the company
The company is a world leader in clutch system and passenger car segment which follows personalized methodology rigorously to ensure customer satisfaction in terms of cost, quality and delivery. This methodology ensures proactive improvements and is founded on the principle of 'right first time'. [16]
The products which they manufacture are clutch assembly - size ranging from 160- 380 mm diameter and pressure plate clutch assembly. Some of the New products which the company is now involved in manufacturing are dual mass flywheel (DMF) and hydraulic clutch release system (CMC, CRC and High-Pressure Pipe). The products are further used in the following applications like passenger cars, MUVs, LCVs, MCVs, HCVs, three wheelers and tractors. [16]
Company’s major strength is derived from its quality strategy and total commitment to quality - TQM, supplier integration and constant innovation. The company is the preferred supplier to automotive majors in the country.
2.2 Description of clutch
Clutches are mechanical devices for engaging and dis-engaging the engine and transmission system of the vehicle at the will of the operator. A clutch cover assembly comprises a clutch cover, a pressure plate, an elastic member, and a lever member. The clutch cover assembly is fixed to a flywheel of the engine for transmitting driving force of the engine to a Driven force. The clutch cover assembly is mainly composed of a clutch cover fixed to time flywheel, a pressure plate within the clutch cover for clamping friction materials of a clutch disc between the flywheel and itself, and an elastic member for engaging the pressure plate with the flywheel.
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A clutch cover assembly is known in which a lever function and an engaging function are done separately. For example, a separate engaging member such as a coil spring or a washer- type spring is located within tile clutch cover so as to apply all engaging force on the pressure plate.
The clutch cover is fixed to an input rotation member. The pressure plate is located within the clutch cover for engaging a friction member with the input rotation member. The elastic member applies an engaging force on the pressure plate to engage the input rotation member.
The lever member is supported by the clutch cover for engaging and releasing the lead of tile elastic member. [4]
The clutch is fixed to an input rotation member. The pressure plate is located within the clutch cover for clamping a friction member to the input rotation member. The plurality of washer-type springs is arranged in series applying an engaging force for engaging the pressure plate with the input rotation member. The lever member, supported by tile clutch cover, is for releasing the engaging load of the washer-type springs.
Fig. 2 Flow Chart of Pressure Plate Clutch Assembly [own]
CLUTCH ASSEMBLY
Pressure plate clutch
Assembly
Cone clutch assembly
Centrifugal Clutch
Semi centrifugal
Hydralic Clutch
Positive Clutch
Cluth Disc Attached to Fywheel
PRESSURE PLATE ASSEMBLY PARTS a. Clutch covers
b. Spring with clamp c. Release levers d. Fork lifter
e. Thrown out -bearings f. Pressure disc
Scope of the project
24 2.3 Operation of the clutch
The clutch allows the power transmission to gear box from engine and it allow the gear to change consequently as vehicle moved from stationary position to higher speed or it made the smooth transmission of power from engine to gearbox.
Friction plate clutch assembly is the most common clutch in automotive, it will work either by fluid or cables. Clutch always engaged when it moving by a power. The pressure plate is attached to the flywheel to exert constant force using diaphragm springs on a drive plate, earlier days’ clutch assembly has series number of coil springs attached to back of pressure plate assembly instead of diaphragm spring. The friction plates placed on the spindle, the input power flows from engine to flywheel and gear box via clutch, the pressure disc has friction lining which is similar to brake lining these linings help to drive the vehicle in smoother way when clutch is engaged. [2]
During the clutch engagement the driver presses the clutch pedal, arm pushes the thrown- out bearings and made the diaphragm springs to pull the pressure disc from clutch plate, the clamp load on the pressure plate disc releases. The pressure plate as larger friction surfaces during disengaging there is no clamp force as the result power transmission from flywheel to gear interrupted and gears ready to change.
During the clutch disengagement the driver releases the clutch paddle, the thrown-out bearing withdraws so diaphragm spring releases the load on the pressure disc as the results clamp load developed on the pressure plate against the clutch disc and power transferred from flywheel to gear box via pressure plate assembly. In hydraulic clutch plate assembly, the pressure developed on the clutch plate assembly activates the hydraulic piston in the master cylinder, the pressure flows through the pipes to slave cylinders placed on the clutch housing.
The slave cylinder attached to the release link. [2]
The types of clutch are shown below.
• Friction clutch (pressure plate clutch assembly) 1. Single plate clutch assembly
2. Multi plate clutch assembly 3. Dry clutch
4. Wet clutch
• Cone plate clutch 1. Internal cone clutch 2. External cone clutch
• Semi centrifugal clutch and centrifugal clutch
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• Conical coil spring clutch
• Positive clutch assembly 1. Dog clutch and spline clutch
• Hydraulic piston clutch
2.4 Single plate clutch
The thesis is mainly focused on the single plate clutch assembly which is the most common clutch plate assembly used in the automotive. The single plate clutch assembly consists of two important subsystems, they are clutch disc and pressure plate assembly as seen in Fig. 3, the clutch plate fixed on the flywheel side where the power is generated and pressure plate assembly placed on the drive shafts, the pressure plate assembly and clutch plates are parallel and concentric with each other. The clutch disc rotates along with flywheel and pressure plate assembly (see Fig.4) is moved along the concentric line of drive shafts, the torque generated on the drive shafts are depend on the contact radius of pressure disc (effective radius of the friction contact). [3]
Fig. 3 Clutch Components in Car [20]
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Fig. 4 Clutch Pressure Plate [16]
Fig. 5 Clutch Plate [16]
27
The single plate clutch assembly consists of the following parts for power transmission:
1. flywheel,
2. clutch disc with friction linings, 3. pressure plate assembly,
a. clutch covers, b. release arm,
c. thrown out bearings, d. pressure plate disc, 4. clutch shaft.
1. Fly wheel
The fly wheel is energy storing member of the engine, it is always fixed with engine and also considered as a part of clutch, the power generated in engine which flows to pressure plate disc from flywheel.
2. Clutch plate or disc
The clutch plate or clutch disc (see Fig. 5) is the driven part of the single plate clutch assembly, the clutch disc as friction lining is made up of abrasive materials and it has series of torsional springs attached unit to reduce the torque fluctuation during clutch operations.
3. Pressure plate
Fig. 6 Pressure plate [16]
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The pressure plate assembly (Fig. 6) is the most important of the clutch which direct the flow of power from the flywheel to gear box. It consists of pressure disc and diaphragm spring;
the pressure disc produces the clamp load on the clutch disc during clutch operations.
a. Clutch cover
The clutch cover is the important member which holds the pressure plate and diaphragm springs unit, it rotates as the pressure plate rotates about it axis. (see Fig. 7)
b. Release arm
The release bearing is the important parts for the thrown out bearing movement, the one end of the release bearing connects to the pivot in the pressure plate assembly and other side connect the clutch pedal lever.
c. Thrown out bearing
The withdrawal fork carrying thrown out bearings and its pivots on a ball, it is mounted in the clutch casing.
Fig. 7 Pressure Plate Assemble [16]
Pressure Ring
Diaphragm Spring Cover Plate
Cover Plate Pressure Ring
Lever Assembly Spring with clamp
29 4. Clutch shaft
The clutch shaft is the integral part of the clutch and gear box assembly. The splined shaft is sliding rotates along with pressure plate assembly during clutch operations. One end of the shaft is pressure plate and another end is connected to the gear box.
2.4.1 Working of single plate clutch
Running clutch is in engaged position, when vehicle want to increase the speed the clutch pedal is pressed. Once clutch pedal is pressed the fork lever press the thrown-out bearing. The pressure plate lifts up and release its contact on the clutch disc using spring. The flywheel rotates independently as engine running, the clutch shaft speed reduces slowly and finally stop its rotation due to rotational inertia.
During the clutch engaging operations, the clutch plate come closer to the pressure disc and get attached to each other using the friction linings. The clutch disc is attached to the flywheel and rotates about the flywheel axis. Since the pressure plate is in contact with the clutch plate the spline shafts rotate along with flywheel and transfers the power to gear box.
Once the clutch pedal is released, the fork releases the bearing and diaphragm spring from its position and the pressure plate and clutch friction lining will approach each other, due to the friction on the both plates the power starts to share from the flywheel to transmission unit. During the engagement the high load on the clutch disc transfer to static pressure plate assembly once inertial load overcomes and starts to rotate in the same RPM. During transfer of load high jerk generated in the clutch plate this fluctuation in the clutch is reduced by using torsional springs. [2]
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3. MANUFACTURING PROCESS OF PRESSURE PLATE
The pressure plate is manufactured by the sheet metal processes. Sheet metal processes have the starting material rolled sheet, at low volume with respect to surface area ratio. The sheet metal processes are involved in changing the process but it is does not changes the modulus. The sheet metal process has no thickness changes, process of shaping the drawing the sheet metal to the required product is called as stamping. The most common sheet processes are shearing, drawing, bending and spinning.
The process of cutting the sheet metal is called as shearing, the primary work of the sheet metal carries with blanking, the shearing process is done by means of alligator shear. Drawing is important process to press the sheet metal from open end to pre-defined die, the die may be in cylindrical shape. [6]
When the cylinder shape is greater than or equal to the radius of base it is called as deep drawing, the deep drawing process is used for the manufacturing of pressure plate. The most common process of making straight work piece into angle through plastic deformation is bending. Spinning is process of pressing the work piece in the rotating blank and converted into hollow shape cylinders and tubes where most of the time spinning processes are carried out in lathe.
Sheet metal process is usually used because most other processes are finding difficulty in processing thin materials. High production rates are often attained, and large production quantities are frequently produced. The bulk deformation process required more forces since the tool costs is less for sheet metal and process is done at room temperature.
3.1 Machining
Machining is the process of cutting or removing the additional materials from the parts, the shape and dimension of the work piece will change as they undergo through the machining process. The tool is harder than the work piece which exert force against the work piece to remove the material. Machining is the dominant manufacturing process because it has only primary and secondary processes. [6]
Mechanical machining is common machining process. The basic mechanical machining process are turning, drilling, milling and shaping. The most important cutting operations are:
➢ Turning: Turning process is performed in lathe machine, in which the work piece rotates and the tool is subjected to travel parallelly i.e. along the center axis of the work piece. This
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operation is used for machining the external cylindrical surfaces for the parts of pressure plate.
➢ Drilling: Drilling process is predominantly used to drill holes by means of drill press or drill bit. The drill press also contributes to improve the inner surface finish of hole by a process termed reaming, similarly thread in a hole can be created by the action of tapping.
➢ Milling: Milling process employs multiple toothed cutters, which contributes to finish complex surfaces. The milling machine might be either a vertical or horizontal machine.
In vertical milling machine the tool’s (cutter) center axis is perpendicular to the machining table. Milling machine with multiple toothed cutters have high metal removal rates.
➢ Shaping: The machining process of flat surfaces by a shaper machine is referred as shaping.
It majorly involves a mono-contact tool which reciprocates on the work piece, the work piece is held across the mono-contact tool in a larger vice, while the ram which accompanies the tool slides to and for in equal strokes for the desired length to reduce the idle time. The shaper is mainly employed to generate smooth leveled (flat) surfaces similar to milling machine, but comparatively the metal removal rates are low due to mono-point tool.
Some of the other methods of metal removal are classified with non-mechanical machining. The four basic non-mechanical process are 1. Chemical milling 2. Electro mechanical milling 3. Electric discharge machining and 4. Laser cutting.
3.2 Joining process overview
The collective term involving welding, brazing, soldering, fastening, adhesive bonding is termed as joining process. It primarily deals with the assembling of many parts/sub- assemblies into a single system. All the above joining process can be included into following three major categories listed as follows: Fasteners, Welding and Adhesives. These categories are highly extensive and includes massive information.
Fasteners: This process of utilises different types of mechanical hardware’s called fastener (bolts, screws, nuts) to join/assemble different parts altogether a to form single entity mechanically through clamping forces, pressure or friction etc. theses joints are non-permanent joints as they do not involve molecular bonding between them. Some examples would be a threaded fastener, pins, and riveting.
Cohesion (welding): It is a permanent joining process which involves of two or more parts that are coalesced at their interaction points by heat, pressure, or both, with or without a filler metal. to produce a localized amalgamation (union) through fusion or recrystallization
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creating a chemical bond. Welding process can be termed as most economical process to adhere/join materials. Welding process are classified by their energy source. The different energy sources used in welding are: electrical, mechanical, chemical, and optical (beam, ray).
Some examples of welding processes are: arc welding, resistance spot welding. friction welding, oxyacetylene welding, and electron beam welding. [6]
Adhesion (gluing): The process of joining two or more material components by synthetic glue. Here good force of attraction is executed between the parent materials and adhesive (adherents) ensuring a better joint. Gluing processes predominantly depends on the bonding or adhesive property. Some of the other adhesive processes are brazing, soldering, and epoxy bonding. Adhesive joining is more popular to join two or more dis-similar parts into a single product.
These joining processes are mainly employed when the structure/part has a very low modulus and also to accomplish a diverse material property: for example, the handle of a kettle should be a poor conductor, whereas the bottom one should be a good conductor, so two different materials need to fused/joined to form a single entity, which is made widely possible by the above joining processes.
3.3 Inspection Process
Inspection process is done using various testing machine. Each quality characteristics are maintained and tested using the following machines like:
1. clamp load tester, 2. wear tester machine,
3. 6 station indexing machine for assembly of clutch roller bearing with load measurement, 4. bearing tester machine,
5. bearing height tester machine,
6. co-ordinate measuring machine (CMM), 7. 6 station indexing machine,
8. dynamic balancing machines.
The Inspection is done based on ISO norms which the company follows and the respected norms for every quality characteristic are mentioned in this chapter.
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3.4 Quality factors involved in the pressure plate clutch assembly failure detections:
The clutch failures cause serious issues for the vehicle and the passengers, when they were at higher speeds it causes serious accident. The clutch plate assembly failure detection is the prior most things to detect earlier. Clutch plate manufacturing and assembly conditions are important to analyze in the quality aspects to reduce the failures.
On analyzing the various parts in the clutch plate assembly will help to reduce the clutch slipping during vehicle running time. In the Fig. 8 List of quality terms involved in the pressure plate assembly are shown. [7]
FRICTION CLUTCH
Pressure Plate Assembly Clutch Disc (Fixed with Flywheel
Components
▪ Clutch covers
▪ Spring with Clamp
▪ Release levers
▪ Fork Lifter
▪ Thrown out -bearings
▪ Pressure Disc Defects
➢ Clamp Load new less
➢ Clamp Load wear less
➢ Bearing Load new more
➢ Bearing Load wear less
➢ Bearing Height more
➢ Bearing Height less1
➢ Parallelism More
➢ Finger Broken
➢ PP lifts less
➢ Fouling
➢ Run out
➢ Unbalanced mass
Quality terms to check the pressure plates
Fig. 8 Depiction of Pressure Plate Assembly [own]
34 3.3.1 Clamp Load
Clamp load is the important parameter which influences the pressure plate contact with clutch plates. The clamp load is a load produced on the pressure plate by the clamps during clutch engagements. It affects the clutch slip during high engine RPMs, and standard procedures are followed to select the clamp and installations.
In this case the clamp load tester is used to measure the clamp load in pressure plate, the standard ISO 16047 norms are followed to find the quality of clamps. The pressure plate set up is placed in the clamp load tester set up and run with various RPMs ranges from 850 to 6000.
The clamp load should be within 4000+/-500 N to 7000+/-500 N. If clamp set up fall way from this range, it will raise slip hence the clamp is rejected.
Possible causes for clamp failures 1. incorrect clamp size,
2. number of treads in clamp, 3. pitch size of clamp,
4. improper machining of clamp, 5. improper bearing settings,
6. improper Bearing Loads influence clamp load.
3.3.2 Clamp Wear
Clamp wear is the important quality parameter that should be verified before installation in pressure plate assembly. Wear testing machine is used to test the wear quality of the clamps.
Clamp is placed in the wear tester machine, where clamps are in contact with rotating plates.
Clamp wear affects the load and life of the clamp, here tester machine rotates with 800 to 900 rpm, clamp wear is measured after 15 min of time interval. Material removal and dimension change in clamp is measured. As per the ISO standards clamp wear should be within 0.5+/- 0.05 mm.
Possible causes for clamp wear 1. material used for the clamp,
2. lubricating materials and temperature, 3. vibration in the clutch assembly.
35 3.3.3 Bearing Load
Release bearing is an important part of the pressure plate assembly. It effectively influences the behavior of clutch plate assembly. Roller bearing is used in the system. Loads in the bearing systems are measured using “6 station indexing machine for assembly of Clutch Roller Bearing with load measurement”.
In this measuring setup pressure plate assembly is set up and measured with different clutch operation conditions like engagement and disengagement with different RPMS, the load developed during this operation are taken as the quality deciding parameter. As per the ISO 286 standards the release bearing load should fall below 1.7 to 2.0 KN and preload should have maintained within 80 to 100 N.
Possible causes for bearing load 1. improper bearing mountings, 2. bearing preload,
3. bearing wear,
4. temperature of bearing, 5. selection of bearing,
6. vibration in the bearing shafts.
3.3.4 Bearing Wear
Bearing tester machine is used to measure the bearing wear as similar to the clamp wear testing machine. The bearing wear should be within 25 micrometers as per the ISO 286 standards.
Possible cause of bearing wear 1. high bearing temperature, 2. improper lubrications, 3. high shear load in bearing.
3.3.5 Bearing Height
Bearing height is important parameter which determines the loads transfer characteristic.
Bearing height tester machine is used to measure the height and clearance values. Bearing
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clearances affect the bearing fittings. As per the ISO 286-2 bearing height variations should be within 10 micrometers.
Possible causes of bearing height change 1. improper bearing design,
2. improper process setting.
3.3.6 Parallelism
Parallelism is the important geometric dimension and tolerance feature.
Parallelism feature where surface is exactly parallel to a datum (reference frame). Parallelism is an orientation control parameters. The parallelism control defines how much a surface part vary from being parallel to a specified reference frame. Here pressure plate is required to be within the parallelism tolerance limit.
Co-ordinate measuring machine (CMM) is used to measure the parallelism features. As per ISO 1101 parallelism of surface should be within 0.08 mm from reference frame.
Possible causes for parallelism 1. improper surface finish, 2. wear in surface finish tool.
3.3.7 Fingers broken
Diaphragm fingers is a part of pressure plate assembly. Fingers in the diaphragm act as a spring during clutch disengagement. Visual inspection is made to find the crakes in fingers.
After pressure plate testing the pressure plates are dismantled and fingers are cross verified.
Possible causes for finger broken 1. improper machining process, 2. dimension (thickness of fingers), 3. improper alignments,
4. higher bearing loads.
37 3.3.8 Pressure plate Lift
Pressure plate lift is one of important parameters which affect the clutch slipping.
Pressure plate assembly is placed in “6 station indexing machine” and the pressure plate lift is measured with respect to release bearing travel. For 8 mm of release bearing pressure plate travel should be 2.0 mm, on exceeding these values are considered as pressure plate lift off.
Possible causes of lift off 1. high release bearing travel, 2. design of diaphragm spring.
3.3.9 Fouling
Fouling is defined as the part interference during pressure plate operations. Visual inspection is made after the testing the pressure plate assembly to cross the part interference.
Unusual noise during the operations is considered as fouling factor.
Possible causes of lift off 1. improper GD and T design, 2. improper machining,
3. in accurate dimension measurement.
3.3.10 Run out
Runout is defined as the feature that vary with respect to reference datum line when parts are rotated in 360 degrees about its rotating axis. 2-Dimensional tolerance data where all point of surface should fall within the tolerance limit, here run out measured in the pressure friction plate.
The dial gauge is used to measure the total run in the part, where pressure friction plate is fixed in rotating disc, dial gauge needle is placed on the measuring surface and disc is rotated to measure the reading and variations at various points. As per the geometric dimension variation in surface should fall within tolerance limit of 30 micrometers.
Possible causes of run out 1. improper machining process,
38 2. wear in tool,
3. surface finish with higher RPMs.
3.3.11 Unbalanced mass (UBM)
Unbalance is defined as an unequal distribution of mass in the systems which causes the mass axis to differ from the bearing axis. During dynamic rotation, the unbalanced mass with radial acceleration rotation causes centrifugal force. This results in higher force on the bearing.
Pressure plate assembly system is placed in the dynamic balancing machines and the centrifugal force produced at different RPMs are noticed. As per ISO 1940/1 eccentricity values should fall within 25 micrometers.
Possible causes of unbalanced mass:
1. blow holes in castings, 2. eccentricity,
3. clearance tolerances, 4. distortion,
5. addition of key and key ways,
6. manufactured unsymmetrical configurations, 7. deposition of unbuilt,
8. corrosion or wear.
In the Tab. 1 the quality factors involved in pressure plate assembly failure are summarized with its individual possible causes and inspection methods.
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Tab. 1 Quality Factors involved in Pressure Plate Assembly [own]
S.no Components Quality factors Description Possible causes Inspection method Measuring Tools Standards Typical values
3.3.1 Clamp Clamp Load new less
1.Clamp load is load produced on the pressure plate to engage the clutch 2.Clamp load influence the pressure plate contact with clutch plates
1. Incorrect clamp size 2. Number of treads in clamp 3. Pitch size of clamp 4. Improper machining of clamp 5. Improper bearing settings 6. Improper Bearing Loads influence clamp load
Manual machine clamp load tester ISO 16047
4000+/-500 N to 7000+/-500 N
3.3.2 Clamp Clamp Load wear less
Clamp wearing will influence the clamp strength
1. Material used for the clamp 2. Lubricating materials &
temperature
3. Vibration in the clutch assembly
Manual machine wear testing machine 0.5+/- 0.05 mm
3.3.3
Pressure plate with bearing assembly
Bearing Load new more
Bearing load is load produced during engaging and disengaging
1. Improper bearing mountings 2. Bearing preload 3. Bearing wear 4. Temperature of bearing 5. Selection of bearing 6. Vibration in the bearing shafts
Semi automatic machine
6 station indexing machine for assembly of Clutch Roller Bearing with load measurement
ISO 286
load should fall below 1.7 to 2.0 KN
& preload should have maintained within 80 to 100 N
3.3.4 Bearing Load
wear less
Bearing wearing will influence the bearing vibration
1. High bearing temperature 2. Improper lubrications 3. High shear load in bearing
Bearing tester
machine ISO 286 25 micrometres
Bearing Height more
1. Improper bearing design
2. Improper process setting ISO 286-2
Bearing Height
less ISO 286-2
3.3.6 pressure friction plate
Parallelism More
The parallelism control defines how much a surface part vary from being parallel to a specified reference frame
1. Improper surface finish 2. Wear in surface finish tool
Co-ordinate measuring machine (CMM)
ISO 1101
within 0.08 mm from reference frame
3.3.7
Pressure plate with bearing assembly
Finger Broken Deviation in Diaphragm fingers
1. Improper machining process 2. Dimension (thickness of fingers) 3. Improper alignments 4. Higher bearing loads
unusual dent or crack
3.3.8
Pressure plate with bearing assembly
PP lifts less Pressure lift off or releasing contact during high RPMS
1. High release bearing travel
2. Design of diaphragm spring Manual machine 6 station indexing machine
For 8 mm of release bearing pressure plate travel should be 2.0 mm, on exceeding these values are considered as pressure plate lift off
3.3.9
Pressure plate with bearing assembly
Fouling Part interference during clutch operation
1. Improper GD & T design 2. Improper machining 3. In accurate dimension measurement
unusual sound
3.3.10 pressure
friction plate Run out
2-Dimensional tolerance data where all point of surface should fall within the tolerance limit
1. Improper machining process 2. Wear in tool
3. Surface finish with higher RPMs Dial gauge tolerance limit of 30
micrometre
3.3.11
Pressure plate with bearing assembly
Unbalanced mass
unequal distribution of mass in the systems which causes the mass axis to differ from the bearing axis
1. Blow Holes in Castings 2. Eccentricity 3. Clearance tolerances 4. Distortion
5. Addition of key and key ways 6. Manufactured Unsymmetrical Configurations
7. Deposition of unbuilt 8. Corrosion or wear
Dynamic balancing machines
ISO 1940/1
within 25 micrometres Geomatical measurement of roller
bearing
Manual machine
unusual cracking sound Quality factors involved in the pressure plate Assembly failure
Bearing
visual inspection
Bearing height tester within 10 micrometres Manual machine
3.3.5
