Unit 9 engineering and maintenance

Question 1

What does effective maintenance ensure?

Answer 1

that equipment works when it should, it also guarantees that plant has a long and productive life

Question 2

How does the directory define maintenance?

Answer 2

as the work needed to keep a road, building, machine, etc. in good condition.

Question 3

The way we carry out our maintenance affects what?

Answer 3

Plant availability - means whether the equipment is ready to be used for production

Production costs

Quality or product

Safety - staff doing non safe stuff to get equipment that always breaks down to work

Environmental impact - can use excessive sources (oil, energy water)

Question 4

What are the goals of maintenance?

Answer 4

To ensure that equipment is in working order

To minimise downtime

To support a safe working environment

To protect product quality

To enable the business to manufacture safe products (e.g. calibrating equipment in order to maintain a critical control point)

To ensure compliance with legislation (e.g. in the case of pressure systems or effluent treatment plants)

To protect the value of the plant

Question 5

What is a maintenance approach?

Answer 5

is how the company opts to maintain all or part of its plant.

No maintenance
Run to failure
Preventative
Predictive

Question 6

Describe the no maintenance approach

Answer 6

does not actually mean no maintenance is carried out.

No maintenance actually means that there is no structured maintenance plan. A no maintenance approach is best suited to very basic non-critical equipment (e.g. lightbulbs) and small businesses

Question 7

What are the five maintenance triggers?

Answer 7

Breakdown – the maintenance activity is carried out because the equipment isn’t working, e.g. a broken water pump.

Time – a period of time has elapsed since the last maintenance activity was undertaken and further maintenance is now due.

Event – a situation occurs that leads to the need for maintenance, e.g. the equipment has been damaged or the product it is producing is out of specification.

Usage – a specified period of usage or a specified volume of product produced has been reached, meaning that it is now time to maintain the equipment.

Condition – the condition of the equipment (or one of its components) is such that it now needs to be maintained, e.g. the thickness of a belt on a bucket elevator has reached its minimum level.

Question 8

What is the advantage & disadvantage of the no maintenance approach?

Answer 8

is that you do not need a skilled maintenance person or team. The disadvantage is that your equipment is likely to be unreliable, potentially unsafe, and might not last very long

Question 9

Describe run till failure maintenance approach

Answer 9

refers to when equipment is only attended to if it breaks down. It differs from no maintenance as the business has both a plan and some resources in place to complete the required maintenance should the plant break down.

Also known as corrective maintenance.

risk of a loss of production

This approach also requires a large spares stock holding, or a large stock of product.

Question 10

What is the RTF best suited for?

Answer 10

most suited to non-critical equipment. This is equipment which will not affect production or lead to an unsafe condition when it fails.

Eg. a cold tap on a hand wash basin or a pressure gauge which is not routinely checked.

Question 11

What is an advantage of rtf?

Answer 11

similar to those for no maintenance in that few resources are required for the approach.

Question 12

What are disadvantages of RTF?

Answer 12

Higher costs – stock, spares, and emergency callouts for maintenance personnel and contractors.

Reduced asset life – the equipment will not last as long as it would if it was maintained more regularly.

Safety issues – people tend to rush repairs under pressure, leading to risk-taking behaviour; the breakdown may result in an unsafe condition.

Maintenance backlog – when used in conjunction with other approaches, RTF maintenance can inhibit existing, planned preventative maintenance. This is because it always prioritises resources for failed equipment rather than working to a planned maintenance schedule.

Poorer equipment performance – the plant will need and use more energy to operate while it is approaching breakdown.

Question 13

Describe Preventative maintenance

Answer 13

Preventative maintenance (PM) is where plant is maintained according to a plan, whether or not it shows signs of wear. PM is designed to prevent equipment failure and breakdowns.

The maintenance triggers are time and usage

vary between a weekly inspection and oil top-up, mini-overhauls every two to three days, through to a complete line or major item overhaul.

Question 14

What is PM appropriate for?

Answer 14

Critical processes where equipment failure will result in lost production or a hazardous situation.

Equipment that you have experience of using and understand when it is likely to fail.

Large companies who can afford a highly skilled and well-organised engineering team.

Equipment that experiences breakdowns due to wear, e.g. pump seals.

Question 15

What are the advantages to PM?

Answer 15

educed downtime due to unforeseen breakdowns and maintenance shutdowns.

Easier production scheduling because we know when the equipment will be shut down for maintenance. Plus, it will break down less frequently than with no maintenance and RTF.

More in-specification product due to equipment that is operating consistently well.

Lower unexpected costs to the business from breakdowns and overtime worked on repairs and restocking.

Question 16

What is PdM?

Answer 16

PdM uses data from equipment monitoring the plant and process to predict when a piece of equipment is about to fail. Also known as condition monitoring, this form of maintenance maximises the availability of equipment by minimising both breakdowns and the time it is stopped for maintenance.

The goal of this approach is to schedule work only as needed and as close as possible to equipment failure

Question 17

What equipment is used for pdm?

Answer 17

vibration analysis, oil analysis, laser alignment of shafts in rotating equipment, and thermal imaging. More traditionally however, temperature, over-voltage, or current and liquid levels have been monitored to warn us of problems.

This automatic monitoring enables tolerances or limits to be set

Question 18

What is pdm suited for?

Answer 18

Mature, well-understood processes where the failure modes (the way equipment fails) are repeated and predictable.

Equipment or processes that can be automatically monitored for temperature, pressure, level, vibration, etc. by a centralised control system or through routine checks by personnel.

Question 19

What is the advantage and disadvantage for pdm?

Answer 19

it keeps equipment in service as long as possible before repair.

dis - PdM is also the most expensive to set up and run

Question 20

Whats a CMMS?

Answer 20

CMMS contains a register of all assets (equipment) and its maintenance requirements. It will issue work orders and record work activities undertaken on each asset.

allows automatic spares ordering, and provides financial information,

Question 21

What are the engineering maintenance tasks?

Answer 21

Cleaning

Lubrication

Health and safety-related checks and tests

Inspection

Tightening

Mechanical fault finding, testing, and repair

Electrical fault finding, testing, and repair

Software/hardware/instrumentation fault finding, testing, and repair

Calibration

Condition monitoring

Question 22

What is Total productive maintenance (TPM)

Answer 22

TPM is called total because it involves not just the maintenance professionals, but all production staff.

also referred to as autonomous maintenance.

Question 23

What are the pillars of tpm?

Answer 23

focused improvement
autonomous maintenance
planned maintenance
training and education
early management
quality maintenance
office TPM
H&S & environment
supply chain

Question 24

what is oee?

Answer 24

OEE is a measure of how well manufacturing equipment is utilised compared to its full potential & seeks to improve overall equipment effectiveness.

Question 25

What is the calculation of OEE?

Answer 25

Availability x Performance x Quality = OEE Availability is amount of time the equipment is running, compared to the planned production time. Performance is how fast the equipment produces output, compared to the maximum output for the production cycle. Quality is the amount of good quality products made, compared to the total produced.

Question 26

What are the goals of TPM?

Answer 26

Zero breakdowns Zero defects Reducing emergency and unscheduled maintenance events to a minimum Eliminating failures and waste due to equipment-related operations

Question 27

What are the 6 big losses of TM?

Answer 27

Breakdowns and unplanned shutdown losses Excessive setups, changeovers, and adjustments Idling and minor stoppages Running at a reduced speed (speed losses) Startup losses, due to breakdowns and stops at startup Quality defects, scrap, and rework due to equipment setup and operation

Question 28

Describe RCM reliability centred maintenance

Answer 28

RCM uses teams of maintenance engineers, operators, and key personnel to ascertain the various ways in which the plant can fail (failure modes) and the consequences of these failures. RCM combines the PM, PdM, and proactive maintenance approaches in order to increase the probability that equipment and components will function as required over their life cycle, with the minimum maintenance.

Question 29

Whats proactive maintenance?

Answer 29

Proactive maintenance works to detect and correct causes of equipment failure. In proactive maintenance, teams of maintenance and production staff use a structured approach to identify how, when, and why equipment fails. They also use it to evaluate the consequences of this failure to the business. Higher risk failures are given a higher priority for maintenance than those with a lower risk.

Question 30

What are the advantages of RCM?

Answer 30

Can be the most efficient maintenance programme, providing high OEE Lowers costs by eliminating unnecessary equipment maintenance or system overhauls Minimises the frequency of major overhauls Reduces the probability of sudden equipment failures Focuses maintenance activities on critical system components Increases component reliability Incorporates root cause analysis

Question 31

What are disadvantages of RCM?

Answer 31

he start-up costs are very high, and savings can take a long time to be realised. RCM is only suitable for a large and complex organisation.

Question 32

whats the 6s method?

Answer 32

method of improving performance by ensuring that the workplace is clean, tidy, and well-ordered. In essence, it makes sure that there is “a place for everything and everything in its place.”

Question 33

What are the 6s'?

Answer 33

Sort - aims to remove from the workplace items that are not needed, such as tools, materials, and parts. Set in order - arranges the material, components, and tools in such a manner that the operatives can easily locate and access them. Shine – requires that the workplace be kept clean, so that is both safe and productive to work in. Standardise – to formalise the sort, set in order, and shine activities, we can standardise their practice so that all operatives can achieve the same results. Sustain – is where the improvements we have made in organising and tidying the workplace are maintained and embedded in the culture of the organisation. Safety to highlight the subsequent improvements to safety achieved through the methodology.