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.

Area	Documentation	Description
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 Direct materials use for assembly,  arrange material list according to the assembly order Hardware such as jig and fixture, torque driver, equipment needed for assembly process Spec and setting of equipment Software and its revision (if applicable) Step by step instruction (prefer picture /photo format) Font must be legible size and language operator can understand 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.

Process Input Machine - Manufacturing Equipment monitoring and preventive maintenance.

After the equipment is qualified and in mass production, all optimized parameter setting should be documented in standard operating procedure (SOP).  Production should follow the same setting to reduce variation in the process output.  There must be performance monitoring of the equipment and total preventive maintenance (TPM) system set up.   A good metrics to use for monitoring the performance of manufacturing equipment would be overall equipment efficiency, OEE, developed by Seichi Nakajima in 1960s. OEE address equipment losses due to plan and unplan shutdown, production adjustment, idling, speed, quality defect and reprocessing : -

Metrics	Calculated based on
Availability	uptime and downtime
Performance	total output, operating machine speed and time
Quality	Yield rate
OEE % =  Availability X Performance X Quality

From the above table, in order to calculate OEE, manufacturers need to setup proper data collection infrastructure which should be included in the planning phase of equipment setup per my previous article. OEE ought to be reviewed by management on regular basis.  There should be a management goal or target set for OEE metrics and investigation must be conducted if OEE does not meet the target.  The better the equipment efficiency,  the higher the OEE value.

In order to optimize OEE, it is utmost important that the equipment is well maintained base on total preventive maintenance (TPM) system.  Total preventive maintenance concept was also founded by Seichi Nakajima.  TPM is aim to achieve Zero Defects, Zero Breakdown and Zero accidents in all functional areas of the organization by involving all levels of people in organization to promote self-maintenance.  The table below shows the eight pillar use in TPM.

TPM Pillars	Elements
Autonomous Maintenance	Person who is using the machine such as operator own equipment daily maintenance through step by step approach that include inspection and cleaning.  This will free up the time of maintenance team to focus on specialize maintenance and improvement work.
Focused Improvement	Small group of dedicated equipment specialist to conduct complicated PM work.  They should review and analyze the OEE data to find incremental improvement opportunity for equipment towards Zero Defects, Zero Breakdown and Zero accidents
Planned Maintenance	1.   Maintenance planning should take into consideration of available resources and number of equipment need PM.   2.   Determine the preventive maintenance interval from daily, weekly, monthly, quarterly to yearly and what are the PM activities should be carried out.   PM interval could also base on production volume. 3.   There should be auto trigger system before PM due date to the management and equipment owner 4.   Ensure the planned maintenance is feasible to be carried out by the maintenance team
Quality management	Equipment has the capability to have auto warning such as andon light if there is error.  All warning must investigated, documented with action plan.  A study must be conducted on how to prevent any error.
Early/Development management	Established proper documentation which include lesson learned on the current equipment from qualification to sustaining phase. Apply the lesson learned in the future new equipment.
Education and Training	Person who conducts preventive maintenance must be trained and certified.  For complicated equipment, the training and certification should be done by equipment supplier.
Safety Health Environment	Sustain a safe and healthy accident free working environment
Administrative & office TPM	Reiterate the TPM principles beyond  manufacturing equipment in the production floor

The recommended activities for preventive maintenance are:

1. Preventive maintenance activities generally consist of inspecting the equipment parts for wear and tear, replace short usage life part before they worn out, cleaning, lubrication for moving parts. 
2. All preventive maintenance action must be recorded. This encompass parts that was replaced.
3. Document PM Activities in checklist format to ensure all PM are carried per PM checklist and according schedule date.
4. After a major preventive maintenance work, actual production parts must be verified before handover for mass production.  This is known as 1^st piece verification done after major PM.

In order to prevent downtime due to unavailability of equipment spare parts, the PM team must setup a spare part management system and keep stock for frequent replaced parts.

Automated manufacturing is mostly suitable for high volume low mix type of manufacturer due relatively longer model conversion time compare to manual/semi auto line. 

Complicated equipment which need  expert maintenance

Manufacturer had perceived that automation will bring cost competiveness into their product, which in actual fact there are also hidden cost in maintenance of the equipment.   There are many  Japanese/Korean/China  multinational  brand suppliers (LCD, battery cells and semiconductor) invested  millions USD to purchase a fully automated manufacturing line,  however there are only a handful who had qualification, monitoring and maintenance system to match the investment made in equipment acquisition.  Automation can produce consistent good or bad parts, therefore a lot of planning by expert must be done to ensure only consistent good parts being manufactured and maintained.

Process Input, machine - Manufacturing Equipment qualification

Automation had been the main driver for cheaper, mass production goods in the consumer market since post world war II.  In electronics gadget supply chain, the higher tier supply chain such as electronics and piece part mechanical component are made from fully automated manufacturing line as this is marketed as mass production commodity part.  Most of the downstream supplier use manual assembly process.  However with the rising labor cost all over the world especially the global manufacturing hub China, most of the manufacturers are now looking into automation solution for their manufacturing process. 

An automated manufacturing equipment

Since manufacturing line automation and equipment is the part of process input, machine, governance process is vital to ensure that variation from automation and equipment is controlled and managed to minimize its contribution to the process variations.    

A fully automated manufacturing line for battery cell assembly process

The qualification of manufacturing process machine is much more complicated compare to jig and fixture qualification featured in the previous article (21 Oct 2017).  As manufacturing equipment is a major capital investment, therefore there should be proper planning before acquisition of the equipment to ensure optimum return on investment (ROI).  Acquisition and setting up equipment is a project by itself, therefore it must follow the proper protocol of project management process which consists of initiating, planning, executing, monitoring & controlling and closing before being hand over sustaining process.  Below are recommendations for activities in each phase:-

Phase	Consideration points/activities recommended
Initiating	Define the purpose of the equipment, function needed and who are the stake holders at both supplier and equipment user. Consider the following factors before investing:- Production volume of the part,  prefer high volume manufacturing Utilization of the equipment Current equipment technology suitability for the manufacturing the part per customer requirement Equipment capability Ease of maintenance Spare parts availability Warranty, service, training provided by equipment manufacturer Reputable equipment vendor who can provide good service to minimize unplan equipment downtime situation.
Planning	Once the equipment is identified for purchasing,  planning should be made for acquisition of the equipment.  This include scope, scheduling, resources- human, space, etc., quality,   cost, and communication from internal to equipment supplier, risk, and procurement of the equipment.  There should be planning for process input and output for each element in planning.
Executing	Performed all the work per planning phase until the equipment is fully commissioned on site.  It would be best to deploy design of experiment study to determine which machine parameter setting would impact output Y and optimization. DOE will be discussed in future article.
Monitoring & controlling	After equipment is fully installed,  there should be monitoring on the performance of the equipment during pilot run which include :- Production rate Yield rate Process capability study on critical to quality parameter Overall equipment effectiveness (OEE) a metric which multiply productivity, quality and availability. OEE is also an important metrics in lean. Please refer to my next article for detail on OEE. All the above study must be based on schedule plan developed during planning phase with goal setting for pilot run.  If any quality or productivity metrics does NOT meet the goal defined during planning phase, there should be feedback loop for improvement before mass production.
Closing & Sustaining	Once pilot run is completed,  then there should be a handover of the equipment to the sustaining equipment department

Design of Experiment approach to optimize equipment setting

The above is very compressed summary of project management approach to setup manufacturing equipment or even an automated manufacturing line.   Project planning should be done by subject matter expert and project management professional (PMP) especially for big automation project. Unfortunately most of the high technology electronic component suppliers who had invested millions of dollar to acquire highly sophisticated are not aware that investing in planning and qualification of the equipment is equally important.   Having the privilege to qualify a few high technology electronic component new manufacturing line during my career as supplier quality manager,  it is ironic that none of the suppliers are aware of the project management approach to set up new manufacturing equipment or line.  There are no proper DOE conducted to find which equipment parameter had an impact product performance follow by optimization. Trial and error study is mistaken to be DOE!

After the qualification of the automated manufacturing line or equipment, it is imperative to setup proper monitoring system and preventive maintenance.  This will be the main focus in my next blog.

Process Input, machine - Jigs and fixture from qualification to maintenance in mass production

In this article, I shall focus on variations contributed by process input, machine.  The word “machine” in this context span from small jigs and fixture, semi automatic equipment to high technology fully automated robotic manufacturing line. 

In electronic industry ecosystem, high tech commodity product such as IC, semiconductor components, battery cells, PCB,  mechanical piece part, memory modules, LCD display,  are produce using  semi to fully automated equipment.  Therefore machine could be the major contributor of process input variations.

Assembly process of fitting all the above high tech commodity parts together to form a finish electronic gadget such smart phone or tablet is more manual process.  Most the assembly process are still make by human hand.  In good manufacturing practices,  we would use jig and fixture  to aid operator in assembly process,  therefore machine is still a contributor to a certain extend.

Machine use to aid manufacturing need to be qualified,  setup by expert and maintained correctly in order to minimize the variation contributed by “machine”.  In part 1 of this article we shall concentrate on jig and fixture qualification  and maintenance in mass production. 

Jig and fixture is used under 2 main situations

Situation	Purpose	Results
Manual manufacturing process	To aid operator in transformation process  such as simple cutting jig or To help support part and guide operator to assemble parts	More consistent part,  such as cutting part with cutting jig,  length will be more uniform
High technology manufacturing process equipment	To reduce the changeover time of equipment by converting a portion of the equipment for changeover of parts	Shorter equipment conversion time

There is a subtle difference between jig and fixture.  Jig is use to aid operator in the transformation of part and fixture main purpose is to support the part during transformation/assembly process.  Good reference to jig and fixture could be found in this link http://engineeringhut.blogspot.my/2010/11/jigs-and-fixtures.html

Jig and fixture  as part of process input, machine, need to be qualified, setup and maintained properly to ensure it helps to reduce process variation to get consistent good quality part.

Recommended practice for Qualification of Jig and fixture

1. Understand why a process needs a jig or fixture,  and conceptualize the design 
2. Design of the jig should into consideration if it will cause handling, ESD problem to the part.  Material selected should not be easily subjected to wear and tear. 
3. Develop jig and fixture drawing with necessary details  :-  dimension and tolerance, critical dimension clearly marked and specify material required for the jig and fixture.
4. Jig and fixture supplier should fabricate the jigs and fixture according to drawing and buyoff the jig and fixture according to design drawing with official first article inspection report.
5. Manufacturer must have identification system which ensure all jig and fixture had a unique identification number for traceability.
6. Manufacturer should create a masterlist for all the jigs and fixture in factory which consist of the following information :-  Jig ID,  Jig name/description,  purpose of the jig,  process used,  FAI date,  drawing,  qualification date and results,  PM required.
7. User factory of jig and fixture should create a process to buy-off jig and fixture which comprise of  :-

• Checking the jig and fixture per drawing and first article with proper report

• Trial  the jig and fixture in production line and record the results of the parts and cycle time. 

• Specify the length of evaluation and how many parts need to be evaluated.

•  Evaluate the key process input Y of the part such as attribute  reject rate, critical to quality parameter variable output.  The qualification best practice would be using process capability index (Cpk/Ppk) of the impacted critical to quality process output Y.  

Fixture which help to support the part , operator do not need to hold part and apply glue result in more consistent gluing process

Typical drawing of fixture

 Jig and fixture could be subjected to wear and tear or shift in performance over time in production,  therefore preventive maintenance is necessary  to verify the jig/fixture on regular basis.

The preventive maintenance of jig and fixture should include the following

1.   Determine the preventive maintenance base on production volume or  interval (months or quarterly)

2.   Establish all the checking criteria for jig and fixture  clearly documented in procedure

3.   There should a master list to track the preventive maintenance due date and auto trigger to the jig and fixture owner in the process.

4.   Create checklist on checking items and record all checking items and condition of jig and fixture. 

5.   Assess if there is any part of the jig and fixture which need to be replaced and record the replacement if necessary.  This can be used to determine if the frequency of the preventive maintenance.

Jig and fixture could help to create a consistent good products if  qualification, set up and maintenance is done properly.  On the flip side it will create problem if there is governance process to manage jig and fixture used.