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 : -

Calculated based on
uptime and downtime
total output, operating machine speed and time
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
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 1st 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.

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