Manufacturing Process Monitoring

“A bad system will beat a good person every time” – W.E. Deming

Nobody wants to be controlled. Politicians do not like any control, once they win the election, a Smoker/Drinker does not want anyone to monitor or control their habit (even in Airplane!), the child does not their parents to monitor their eating and studying habits.

But, can anyone survive without adequate control? Same is true for any organization, where many employees work together to achieve a common goal. In the manufacturing process, monitoring and control become even more important for ensuring customer satisfaction, reducing waste & variation in the process and continual improvement. The standard emphasizes both a process approach, as well as the need to use a review or checking phase, which you can from the Plan>Do>Check>Act approach (PDCA).

As per IATF 16949: 2016, following are the definitions related to Manufacturing Process Control.

Manufacturing (Clause 3.1): the process of making or fabricating – production materials; – production parts or service parts; – assemblies; or – heat treating, welding, painting, plating or other finishing services.

Reaction Plan (Clause 3.1): Action or series of steps prescribed in a control plan in the event abnormal or nonconforming events are detected.

Escalation Process (Clause 3.1): the process used to highlight or flag certain issues within an organization so that the appropriate personnel can respond to these situations and monitor the resolutions.

Control Plan (Clause 3.1): documented description of the systems and processes required for controlling the manufacturing of the product.

Some of the IATF subscribing OEM have their specific requirements related to Monitoring & Control of Manufacturing Process.

As per ISO 9001 & IATF 16949 Standard, clause 9.1.1.1, following are the key expectations.

• Manufacturing Controls: For any manufacturing process, it is pertinent to ensure that inputs from documents like Process Flow Chart (PFC), PFMEA (Process Failure Mode & Effect Analysis), Control Plan etc. are effectively implemented. It includes Measurement techniques (CMM, Roughness tester etc.), Sampling Plan (once in a shift/once in 2 hours / 5 consecutive pieces etc.), Acceptance criteria (within tolerance, Cp, Cpk etc.), Records (initial job setup, Laboratory test report, process change, tool change, operator change etc.), Reaction plan (when process/product is not meeting specification, approved process not followed etc.).   

Example:

for Welding Process

PFMEA: Welding strength may be a ‘special characteristic

Control Plan: Symbol of special Characteristic like MAJOR

Process Control: Weld penetration

Sampling plan: to check the welding strength of the first 2 pieces

Acceptance criteria: nugget should come out during weld strength test

• Manufacturing Process Capability: As required by the customer or organization, process capability studies (Cp, Cpk, Pp, Ppk etc.) are conducted for new and ongoing manufacturing processes. These studies are generally conducted for Special Characteristics. Records of such studies need to be maintained for customer review and approval. In many cases, the process capability study is not possible. In such a situation, alternate measurement techniques have to be deployed to verify the effectiveness of the manufacturing process. The intent of such studies is to verify compliance to existing controls or to add additional process controls, where needed. Whenever process capability targets are not met, the organization has to take suitable action plan with target date and responsibility.  

Example:  

i           for Euro VI Emission norms, many organizations have established new/amended manufacturing processes. Process capability study is important to verify compliance with legal requirements.

ii          for batch process like heat treatment or Electroplating, process capability studies are not adequate. In such cases, an alternate method like frequent process validation, mistake-proofing (poka-yoke) or 100% inspection may be implemented.

• Significant Process Events: During the production process, events like perishable tool change/machine repair/overhauling of machine/revision of process parameters after revalidation of the manufacturing process are common. The expectation of the standard is to record such events so that its impact can be tracked back when needed.

Example:  

1. In a CNC machine, the cutting tool has been replaced after a certain frequency.
2. In case of a breakdown in forging press, repair has to be conducted.
3. During annual revalidation of the surface treatment process, process parameters like Temperature, Time, speed etc. may be revised.
4. Heat treatment furnaces are overhauled at a certain frequency.

• Reaction Plan: During the manufacturing process, there is a possibility that process or product do not meet the requirement. In such a scenario, the organization should have an action plan to manage such a situation. Some of the possible reasons could be ‘not meeting process capability guidelines, poka-yoke failure, measuring equipment not available’ etc. The reaction plan should be comprehensive so that it can protect both internal and external customer. The possible actions could include 100% inspection, rejection, scrap, how to correct the process, additional sampling on the products etc. If needed, as part of an action plan, customer should also be communicated about the failure and actions taken.

Example: for the Welding Process, during the in-process inspection, if welding strength is found less than a requirement, the reaction plan could be

stop production

call supervisor

contain the welded components

review the performance of a welded component of the previous lot

check the competency of the operator

do job setup again

check welding strength

increase sampling frequency

revalidate process parameter etc.

• Records of Process Changes: Generally, manufacturing processes are approved internally or by customer. In a real-life scenario, there can be a possibility of process change due to

approved operator change (absenteeism)

approved machine change (breakdown)

approved material grade change (non-availability or high cost)

sequence of process flow change (improving productivity or machine breakdown).

In all such cases, the organization has to record the actual date when these changes happened. The intent is to track back, in case of any customer complaint or internal rejection.    

Example: A plastic moulding machine (250 ton) is approved by the customer along with its process specifications and qualified operator. In case of machine breakdown and to fulfil production schedule/delivery, the alternate machine has to be used. In this situation, unapproved machine, process parameter and operator may be used.  

Key Performance Indicators

• OEE%
• Internal Rejection (PPM)
• Scrap (PPM)
• Process Capability Performance
• Customer Rejection (PPM)

Benefits to Top Management

• Enhanced Customer Satisfaction
• Process Efficiency Improvement
• Cost Saving
• Employee morale improvement

Some question to ponder:

• How often in the manufacturing process, in-case of tool change or machine repair, the information is recorded?
• Whether Reaction plan is worth to implement? In the majority of the cases, the reaction plan is ‘Stop the production & call supervisor!’
• How often process changes in the manufacturing process are recorded?
• How often organizations identify special characteristics, if not identified by the customer, for the fear that additional controls have to be implemented!!
• How often a process capability study is conducted online? In the majority of the cases, it is postmortem, when values are fed in software to know the trend and capability values!

References:

IATF 16949: 2016

iatfglobaloversight.org

AIAG SPC Manual 2^nd Edition

AIAG APQP 2^nd Edition

This is the 44^th article of this Quality Management series. Every weekend, you will find useful information that will make your Management System journey Productive. Please share it with your colleagues too.

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