The most dynamic process input – Method

We had study 3 major process inputs in the past 9 articles,  measure, man and machine.    In this article  we shall put our attention to an important process input, method,  which govern the transformation process from raw material to final product in the shop floor. 

Process input Method

Through my experience, this process input is the most misunderstood  among 6 process inputs where majority manufacturer thought  method is equivalent to work instruction documentation.  Work instruction documentation is actually outcome of the method. 
A good method should be developed through the following rigour :-
  1. Understand customer requirement, process output and overall end product.  It is in the best interest for the process owner  to understand how each process output relates to final product which will eventually be sold. 
  2. Study customer documentation such as drawing or customer specification. 
  3. Develop transformation process step required to transform raw material to finished product according to customer requirement
  4. Determine the process control needed for each transformation process step.  Example in plastic injection molding process which mold plastic pellets to  phone casing,  molding parameter need to be control and the final characteristic such as case dimension and appearance need to check.
  5. Study best way to perform the each transformation step which include :-  motion study,  fatigue study,  operator egronomic.  It should be simplest method to transform a product.
  6. Considered the human and product change over in manufacturing line  (will be discussed further in consecutive article)
  7. Once the best method is identified on how to transform  raw material to finish product,  there it should be documented.  All operators involve in product transformation should be trained according to documented method.

The scope of method is actually very wide from individual unit operation of  product transformation steps to whole manufacturing process from raw material to  finished product.   The table below show different type of method documentation with its application.

Single transformation process step
Work instruction, Standard operating procedure
Equipment operating procedure
Detail description with work step in a single work station or single unit operation eg assembly one piece part to another piece part thru torque screw.
Start to end transformation process from raw material to finished goods
Process flow chart,
A Process Flow Diagram is a flow chart linking individual process steps to form a manufacturing system.
Process management plan
Written summary of the methods and systems used to control production parts and processes to address product and process characteristics and requirements for control. Aims at minimizing variation
Developed from process failure mode effect and analysis (PFMEA)

Process flow chart which give an overview of the process from raw material
to finished goods

Good documentation should consists of the following :-

Type of document
 Items needed in the documentation
Process management plan
Should in table format with 4 main sections heading follow by sub heading
Product/ Process information
Process ref ID number (per process flow diagram
Process Name/Operation Description
Machine, Device, Jig, Tools for Manufacturing
Characteristics number, Product/Process & class
Product output (Y) product critical to quality metric such as dimension
Process input (X),  machine setting,
Control Methods for critical quality metric
Product/Process Specifications/Tolerances
Evaluation/Measurement Technique
Sample Size and Frequency
Control Method – run chart, SPC, auto trigger etc
Reaction Plan
Action performed if found non compliance and  prevent non compliance part from reaching the customer

Work instruction/SOP/
Equipment  operating instruction
Work instruction should be in standard template with the following items
  1. Direct materials use for assembly,  arrange material list according to the assembly order
  2. Hardware such as jig and fixture, torque driver, equipment needed for assembly process
  3. Spec and setting of equipment
  4. Software and its revision (if applicable)
  5. Step by step instruction (prefer picture /photo format)
  6. Font must be legible size and language operator can understand
  7. Photo must be clear  and with color

Process Management Plan

Left:  Work instruction which is difficult to follow
Right : Improved work instruction with picture

No matter how good a process method is being established,  it will be pointless if it is not documented properly  as documentation is a communication tool to instruct operator to work according to work instruction.    In any organization,  it would be foolish to depend one person who knows the process to work without any documentation of the process.  What will happen if this person leaves the company.

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Continuous Improvement Program CIP - 6sigma Methodology