Maintenance Versus Production

Stamping Journal Cover
By Greg Messel, and from VIPGroup: Robert Burke & Patrick Lucansky

Total productive manufacturing (TPM) is a customer-focused approach to business aimed at satisfying both the customer and the company's needs. It promotes common goals between maintenance and operations, establishes training systems, encourages audits and diagnosis tools, and reduces process variability.

The process starts with a marriage between maintenance and production, two dissimilar groups that work together but often have different or even opposing goals and objectives. IT requires total participation by operators, maintenance personnel, management and engineering.

TPM main objectives are to:

  1. Change the culture.
  2. Optimize processes and equipment effectiveness.
  3. Involve all employees in the process.
  4. Develop a proactive process for operations and equipment maintenance personnel.

To meet customer demands and make TPM a sustainable tool, stampers must start by identifying optimal rather than acceptable conditions for equipment, materials, and employees. Actions should be focused on understanding machine principles and mechanisms, treating all losses as serious performance issues, measuring performance accurately and tracking results.

In a TPM environment, production is responsible for producing parts at the required quantity, quality, cost, and price. Maintenance is responsible for ensuring that the presses run at optimum production levels with minimal planned and unplanned down-time.

By uniting production and maintenance with a common goal of, for example, surpassing customer expectations, stampers can realize increased cooperation, productivity, part quality, shop cleanness, and a team approach to maintaining equipment. 

Having these two groups work together creates an increased effort not only to repair and maintain equipment but to improve its capability. Its a partnership aimed at improving or eliminating nine major categories of equipment losses. 

Nine equipment loss categories:

  1. Unplanned Downtime. Equipment breakdowns that require repair, waiting for maintenance and run parts - ends when equipment is ready to run.
  2. Planned Downtime. Any scheduled maintenance activity including cleaning, preventive maintenance, equipment upgrades, all wait times - ends when equipment is ready to run.
  3. Setup Time. Time spent changing over to the next product, process, or recipe and includes the time from the last good product to the first good piece of the next product produced.
  4. Minor Stoppages, Stoppages that can be resolved within six minutes.
  5. Idle Time. Occurs when there is no work, no operator available or bottle-necked equipment.
  6. Speed Loss. The difference between running at an optimal speed and the current run speed.
  7. Engineering or Validation Runs. All nonproductive activity which includes the time from the last good piece from the prior production run to the first good piece of the next production run.
  8. Rework and Scrap. Equivalent time to produce all units requiring rework or scrapped parts and all downstream activities impacted by the rework or scrap.
  9. Quality Time Loss. The time the process is stopped to correct non-compliant issues, inspecting, and accepting non-compliant product produced. 

Why total productive manufacturing?

When a machine breaks down the impact is rarely felt because most stampers have high levels of in-process material to run. However, as down-time lengthens, upstream processes run out of material and eventually shut down. In regulated industries, this can mean split lots or spoiled work. Similarly, downstream processes starve because of a lack of parts and are forced to shut down. 
As companies move toward lean enterprise, work cells, and flow manufacturing, breakdowns have an immediate impact by stopping the entire process, which affects the entire systems performance. In a lean enterprise, operations cannot be moved to another machine, and there is no inventory to keep others machines in the cell running. This forces the operation to deal with the breakdown immediately and put measures in place to prevent a recurrence.

Optimizing Equipment

To move to a productive program, a stamper should begin by identifying the causes for the high frequency of breakdowns (dependability) and the reasons for long repair times (maintainability). 

Two common indicators of equipment performance are mean time between failure (MTBF) and mean time to repair (MTTR). MTBF indicates the dependability of the equipment: MTTR indicates the maintainability of the equipment. 

Four main causes of frequent equipment breakdowns are:

  1. The way equipment is used. It's common to see part requirements that force presses outside of specified designed characteristics. Presses used outside of the manufacturer's specifications can break down more frequently and should be closely monitored.
  2. The level of maintenance. Many stampers wait until components break down before replacing them. Equipment that is regularly lubricated and parts such as bearings that are changed on a timely basis can reduce equipment downtime.
  3. The complexity of the equipment. Equipment with hundreds or thousands of components is more likely to break down than machines with fewer components. This does not mean that higher break down rates occur from increased automation, but rather from a higher level of complexity. The integration of numerous complex components into a single system can increase the risk of failure.
  4. The robustness of the equipment design. It is important to know the extent of the conditions and ranges which the equipment was designed to perform. Operating outside of the ranges increases the malfunction.

Giving Everyone a Voice

For this program to survive, a cultural change must occur. Production and maintenance must be a team with the goal of meeting customer demand profitability. Sustainability occurs when everyone believes in the program, realizes the benefits, and takes ownership of the process. Their efforts should relate to reducing any of the nine losses.

In a TPM environment, all maintenance and manufacturing personnel share, listen, and support  improvement suggestions and ideas. Operators are made responsible for maintaining their equipment and begin to take ownership of its performance. Downtime is used for cleaning and improving the work area, and attention is focused on anticipating problems. 

As operators are given more responsibility in maintaining equipment, they also have the opportunity to suggest modifications to facilitate maintenance.

Measuring Progress

Stampers can measure changes by incorporating a disciplined corrective action (CA) program into their standard operating practices. ISO certification and good manufacturing practices. TPM also provides for enhanced equipment performance resulting in lead-time reductions, increased flexibility, and proactive maintenance. Operators know their equipment and processes and use root-cause analysis to identify and resolve issues.  

Key performance indicators such as downtime,  scrap and on-time delivery also can monitor progress and continually remind everyone what is at stake.

New way of thinking... doing business.

This new way of thinking works not only on the shop floor but across all areas of a company. Any area that uses equipment such as copiers, measuring instruments, computers, and telecommunications equipment can apply TPM principles. 

The TPM concept has a broad scope, focusing on the customer, the organization, and employees. It involves the whole organization in identifying, resolving and preventing issues, which benefits the customer and the stamper's bottom line.