Sheet-Metal Forming Processes - PowerPoint

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   Pareto analysis:
   The cause-and-effect diagram
   Pareto Analysis
       a simple method for separating the major causes (the
        'vital few) of a problem, from the minor ones ('trivial
        many')
       Pareto Analysis can help prioritize and focus resources
        where they are most needed. It can also help you
        measure the impact of an improvement
       80-20 rule - a large proportion of problems resulting
        from a small proportion of the causes
       Data is collected, analyzed and a pareto diagram
        constructed
       TQM will focus on the small proportion of causes that
        have very large no. problems (I.e to the left of the
        diagram)
Cause-and-effect diagrams
 There are three basic types of cause-and-
  effect diagrams used in industry:
1. Dispersion analysis: Most frequently used, allows
   problem solvers to focus on why variations occur.
   Consists of four branches: workers, materials,
   inspection, and tools.
2. Cause enumeration: List of all of the causes of
   variation that can affect a process. Helps identify the
   sets of common causes that inhibit a process from
   meeting specification.
3. Production process classification: Used to study
   an entire process – shows all machines used in a
   sequential process and the possible cause at each
   machine that could result in a defective product.
   Cause -effect diagram (fishbone diagram)
Quality of Design Versus Quality of
Conformance
   A process in Japan offers a quantitative approach to analyzing
    the quality aspects of design in products. The Process known as
    TQM address the quality problems that are built into the
    product and process during their design.

   Quality of design area:
     A. The market research activity is where customer needs and
        expectations are defined
     B. The product and process development activity is where
        standards and specifications for the product and process are
        developed.
     * 80% of the quality problems occur from bad design and poor
        process
Quality of Design Versus Quality of
Conformance

   Quality of conformance:
    A. Manufacturing: Develop a product with
      nearly zero defects
    B. Delivery: Provide safe and effective
      delivery of the product to
      retailers/customers
    C. Customer Service: Provide full 100%
      customer service and support
Defect-Free Design Philosophy
   In 1798, the US government needed a
    large amount of muskets, quickly.
   This was hard to come by then due to
    product variability.
   Eli Whitney worked to reduce the
    variability in the parts.
   The process today is call “the six-sigma
    design process”
    Process Capability Index - Cp
   A measure of the inherent capability of the
    process to produce parts that meet the
    design requirement.
   The larger the Cp, the more likely the parts
    will satisfy the production requirement.
   This is calculated by dividing the total
    tolerance by six times the standard deviation.
Defects-per-unit Benchmark
   Used to judge a superior manufacturer
   Number of defects per unit in complex
    products
       Superior manufacturer has a defects per unit that
        approaches zero
       Typical manufacturer has a defect level of 5 or
        higher
   The key to achieving level of quality lies in
    the capability index for the critical design
    tolerances on each of the parts used in the
    complex assembly.
      Seven Steps to Six Sigma Capability
   Zero Defects

1. Identify the product / characteristic

2. Identify the critical dimensional and
functional characteristics.
3. Identify process sequence.
4. Determine the nominal design/ tolerances that
allow for easy assembly.
    Seven Steps to Six Sigma Capability
5. Determine the process capability
6. Check the capability index, Cp
7. If Cp is not equal to or greater than 2, change
the design until it does.
Questions ???