To tal Quality - Assignment Brief This assignment is based on a case study in which a consultant (you) is asked to investigate a problem with an automotive assembly that is causing the company...

pin and shackle assembly
5/28/2012
Review & Recommendations | students Name
ABC
INC.
PIN AND SHACKLE ASSEMBLY
TABLE OF CONTENTS
1 INTRODUCTION 2
2 PROBLEM DEFINITION 2
3 MEASURE THE PROBLEM 2
3.1 ESSENTIAL TOLERANCES 3
3.2 CRITICAL DIMENSION 3
3.3 SAMPLE DATA 4
4 ANALYSIS OF DATA 7
4.1 SUPPLIER A 7
4.2 SUPPLIER B 8
4.3 SUPPLIER C 9
4.4 COMPARISON OF SUPPLIER A, B, C 10
4.5 SUPPLIER D 10
4.6 SUPPLIER E 11
4.7 SUPPLIER F 12
4.8 SUPPLIER G 12
4.9 COMPARISON OF SUPPLIER D, E, F, G 13
5 SETTING UP TOLERANCE LEVELS 14
6 SETTING CONTROL LIMITS 14
6.1 CHECKING SAMPLES FOR CONTROL LIMITS 15
7 SUPPLIER RECOMMENDATION 18
7.1 DEFECTIVE MATERIALS: 18
8 STRATEGY 19
8.1 IMMEDIATE STRATEGY 19
8.2 LONG-TERM STRATEGY 19
9 CONCLUSION: 20
INTRODUCTION 1
The report is with reference to your work order to ABC INC. for analysis of the
Pin and Shackle assembly problem. We have analysed the product and
concluded on all probable causes of defects. Our observations and analysis of
the above problem along with recommendations is presented in this report. We
have analysed sample products from all of your suppliers and given a rating on
their quality standards. As quality is paramount for customer satisfaction we
have proposed to set stringent quality standards and control charts for Pin and
shackle assembly. Through the first phase of the report we have defined the
problem and listed the data collected for analysis of the problem. In next section
we have analysed the problem and presented our recommendations. In last
section we have presented the future strategy for your company and conclusion
of our study.
PROBLEM DEFINITION 2
It‟s important to understand the product to detect the problem. The pin and
shackle assembly is a high precision automotive assembly. The assembly has
three separate parts Pin, shackle and Cotter. Based on our study we find that
the three parts need to join together to form the complete assembly and the
precision level of all three components is vital for it to function as a unit. The
cotter is fitted with nut and washer. The problem occurs in two conditions:
 The cotter protruding head is so long that threaded part of cotter
ends and the nut cannot be tightened.
 The cotter protruding head is so short that threaded part is
insufficient for nut and washer.
The three components come from different vendors and they have not been
given any specification or design drawings. The product design at present is
based on sample specification. The acceptance criterion/ tolerance level for
each component is not specified. However Cotter protrusion gives a tolerance
of 9 to 19 mm for the unit to be acceptable and function. Any protrusion
variation more than the above values will result in problems mentioned above.
MEASURE THE PROBLEM 3
Problem of misfit occurs when the components are purchased separately. The
causes of problem are shown with a cause effect diagram.
Fig 1: Cause effect diagram for the pin and shackle problem
The further detailing of the causes will require analysis of the supplier
processes and so has been excluded from the report.
3.1 ESSENTIAL TOLERANCES
From the above four causes we can conclude that he vital dimension for the
pin is dimension „A‟ and for shackle it is dimension „B‟. So we need to set
tolerances for the above two dimensions. The quality of cotters has shown no
deviation however the critical dimension for it will be the end diameter and the
converging slope.
3.2 CRITICAL DIMENSION
Fig 2: Product Diagram
If we observe the product diagram we can see that the pin is a circular
component and shackle has a circular opening for it. The centreline of the
opening will be critical for the pin to match the dimension „A‟. Even if the pin
shows a value within tolerance level still the acceptance of the unit will depend
on dimension „B‟. If in case pin has higher diameter then it will not fit in the
shackle slot and if smaller then it will slip out. So the critical dimension is „B „.
The dimension „B‟ is set by the shackle manufacturer while making the hole for
the pin. The centreline of this hole is critical for overall performance of the
assembly.
3.3 SAMPLE DATA
Below data are samples of dimension ‟A‟ and „B‟ from various suppliers and
some statistical measures for analysing them. The analysis would be done in
next section.
Scatter plot shows the deviation of the sample about its mean or objective
value. A scatter plot of closely spaced sample values shows less variation as
compared to large spread out points. Typically supplier A & F have all values
within a thinner band indicating less variation in sample .
Chart 1: Scatter plot for Supplier A (Dimension A)
18.85
18.9
18.95
19
19.05
19.1
19.15
0 5 10 15 20 25 30
Supplier A
Supplier A

Chart 2: Scatter plot for Supplier B (Dimension A)
Chart 3: Scatter plot for Supplier C (Dimension A)
18.95
19
19.05
19.1
19.15
19.2
19.25
0 5...