Total Productive Maintenance (TPM)

Total productive maintenance (TPM) is a concept developed by the Japan Institute of Plant Maintenance (JIPM) Tokyo in the late 1960s. TPM is the key for the operational excellence of many Japanese companies. TPM is a maintenance programme that involves a newly-defined concept for maintaining plants and equipment. The goal of the TPM programme is to mark­edly increase production, while at the same time increasing employee morale and job satis­faction. The TPM programme closely resembles the popular TQM programme. Many of the same tools such as employee empowerment, benchmarking, documentation, etc. are used to implement and optimize TPM.

All manufacturing organizations possess industrial equipment for various processes in the production of goods. Similarly services organizations also use various gadgets such as computers, printers, facsimiles, photocopies, etc. to aid their daily operations. Maintenance of facilities and equipment is done to ensure that these are in good working condition at any point of time. If breakdowns occur, necessary repairs should be conducted in order to bring them back into running condition as early as possible. Maintenance management involves planning, organizing and controlling maintenance activities such that the overall mainte­nance cost is minimized.

TPM is an approach with the core objective of organizing a workplace to prevent all losses and achieve zero defects, zero breakdowns, zero accidents and zero pollution in the entire production system lifecycle. This is done by involving all the employees and covering the entire organization in the form of small competing teams to establish a culture for maximiz­ing production efficiency. It strives to maintain optimum equipment conditions in order to prevent unexpected breakdowns, speed losses and quality defects arising from process activi­ties. Box 14.1 discusses TPM implementation at HUL.

1. History of TPM

TPM evolved from TQM and is an innovative Japanese concept. The origin of TPM can be traced back to 1951 when the Japanese companies introduced preventive maintenance. However, the concept of preventive maintenance was taken from the work of Dr W. Edwards Deming. In 1960, Nippon Denso was the first company to introduce plant-wide preventive maintenance. Preventive maintenance is the concept wherein, operators produced goods using machines and the maintenance group was completely dedicated to the work of main­taining those machines. With the automation of Nippon Denso, maintenance became a problem as more maintenance personnel were required. So the management decided that the routine maintenance of equipment would be carried out by the operators. This is referred to as autonomous maintenance, one of the main features of TPM. Only the essential mainte­nance work was carried out by the maintenance group.

Thus, Nippon Denso that already followed preventive maintenance also added autono­mous maintenance to activities undertaken by the production operators. The maintenance crew went into equipment modification for improving reliability. The modifications were made or incorporated in all new equipment. This led to maintenance prevention. Thus, pre­ventive maintenance along with maintenance prevention and maintainability improvement gave birth to productive maintenance. The aim of productive maintenance was to maximize plant and equipment effectiveness to achieve optimum lifecycle cost of production equip­ment. By then Nippon Denso had also formed quality circles. Based on these developments, Nippon Denso was awarded the Distinguished Plant Prize for Developing and Implementing TPM by the Japanese Institute of Plant Engineers (JIPE). Thus, Nippon Denso of the Toyota group became the first company to obtain TPM certification.

Box 14.1 JIPM Awards TPM Certification to HUL

Hindustan Unilever Limited (HUL) has been in India since 1931 and has played a key role in the industrial development of India. It is India’s fastest growing and the largest consumer goods com­pany with leadership in home and personal care products, beverages and ice creams.

HUL’s regional office in Mumbai has bagged the TPM Level-One certification from the Japan Institute of Plant Maintenance (JIPM), which accords TPM certifications worldwide.

HUL implemented TPM in its sales operations in order to re-orient its office processes. The objec­tive was to become the best-in-class service provider. HUL has rolled out TPM in sales operations at its three regional offices—Chennai, Delhi and Kolkata. These offices will be audited by JIPM. HUL introduced TPM in its sales operations after deriving benefits from it in its manufacturing operations.

Some of the benefits obtained after implementing TPM are improved delivery time to redistribu­tion stockists, drastic reduction in damaged stocks, significant improvements in claims settlement and in-transit stock display.

2. Objectives of TPM

The main objectives of TPM are:

  • TPM aims to maximize overall equipment effectiveness (OEE).
  • TPM establishes a thorough system of planned maintenance (PM) for the equipment’s entire lifespan.
  • TPM should be implemented by cross-functional teams from various departments.
  • TPM involves every single employee from the top management to workers on the shop floor.
  • TPM is based on the promotion of planned maintenance through autonomous small group activities.

3. Overall Equipment Effectiveness (OEE)

TPM strives to achieve OEE by maximizing output while minimizing input. The input con­sists of labour, machine and materials while the output consists of production (P), quality (Q), cost (c), delivery (D), safety, health and environment (S) and morale (M). TPM strives to maximize output (PQCDSM) by maintaining ideal operating conditions and running equipment effectively. To achieve OEE, TPM concentrates on eliminating “six big losses.” Figure 14.2 shows the OEE model.

4. Six Big Losses

The six big losses can be grouped under three main heads—availability (downtime), perfor­mance rate (speed losses) and quality rate (defects).

Availability (downtime): Downtime results because of

  1. Equipment failure from breakdowns.
  2. Setup and adjustment from exchange of die, tool changes.

Performance rate (speed losses): Speed losses result on account of:

  1. Idling and minor stoppages due to abnormal operation of sensors, blockage of work on chutes, etc.
  2. Reduced speed due to discrepancies between the designed and the actual speed of equipment.

Quality rate (defects): Defects arise due to:

  1. Process defects due to scraps and quality defects to be repaired.
  2. Reduced yield from machine startup to stable production.

Overall Equipment Effectiveness = Availability x Performance Efficiency x Quality Rate

OEE = A x PE x QR

These terms are explained below:

Availability (A) is the duration of the time for which the equipment is actually available to do useful work, out of the time it should be available. It is calculated as below:

Availability (A) = MTBF/MTBF + MTTR

Where MTBF = Mean time between failures (a measure of equipment reliability)

MTTR = Mean time to repair (a measure of equipment maintainability)

Reliability is the consistency of performance. It is measured by the length of time a product can be used before it fails.

Durability is the ability of a product to continue to function even when subjected to rough and frequent use.

Maintainability is the ability of a product to return to operating conditions after it has failed.

Alternatively, availability can also be defined as:

Availability (A) = Loading time – Downtime/Loading time

Performance efficiency (PE) is a measure of how well a machine performs, while it is running.

Performance Efficiency (PE) = Rate Efficiency (RE) x Speed Efficiency (SE)

Alternatively, performance efficiency can be defined as:

Loading Time – Downtime

Quality rate (QR) is a measure that indicates the equipment’s ability to produce non­defective products. It is defined as:

Example:

Working hours per day = 60 minutes x 8 hours = 480 minutes

Loading time per day = 460 minutes

Downtime per day = 60 minutes

Operating time per day = 400 minutes

Output per day = 400 pieces

Types of downtime:

Setup: 20 minutes Breakdown: 20 minutes Adjustments: 20 minutes Defects: 3 per cent

Availability (operating rate) = (400/460) x 100 = 87 per cent

Ideal cycle time = 0.5 minutes per product

Actual cycle time = 0.8 minutes per product

Operating speed rate = (0.5/0.8) x 100 = 62.5 per cent

Net operating rate = 400 pieces x 0.8/400 minutes x 100 = 80 per cent

(100 – Net operating rate) reflects losses caused by minor stoppages

Performance rate = 0.625 x 0.800 x 100 = 50 per cent

Quality rate = 98 per cent

Overall equipment effectiveness = 0.87 x 0.5 x 0.98 x 100 = 42 per cent

Source: Poornima M. Charantimath (2017), Total Quality Management, Pearson; 3rd edition.

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