GG50GUIDE

COST-EFFECTIVE PAINTAND POWDER COATING:MATERIALS MANAGEMENT

Be S o l v e n t W i s e

GOOD PRACTICE: Proven technology and techniques for profitable environmental improvement

© Crown copyright. First printed 1997. This material may be freely reproduced except for sale or advertising purposes.

Printed on paper containing 75% post-consumer waste.

COST-EFFECTIVE PAINTAND POWDER COATING:MATERIALS MANAGEMENT

This Good Practice Guide was produced by the

Environmental Technology Best Practice Programme

Prepared with assistance from:

March Consulting Group

This Good Practice Guide is one of four complementary Guides providing advice on cost-effectivepaint and powder coating. It is aimed at paintshop and production managers whose operations useorganic solvents, eg in paint, for thinning paints, cleaning equipment or degreasing.

Certain organic solvents, also known as volatile organic compounds (VOCs), can give rise toemissions which contribute to low-level air pollution and directly to global warming.

This Guide explains how a company can reduce its costs and VOC emissions by focusing on itsmaterials and paintshop management.

Paint and solvent consumption can be readily reduced by no-cost and low-cost good housekeepingmeasures, and the implementation of a structured approach to waste minimisation. IndustryExamples within this Guide illustrate the savings that can be made through good housekeeping andother measures.

This Guide highlights ideas that will:

■ save money;

■ save time;

■ use less paint and solvent.

Reducing solvent consumption may help some companies increase capacity without needing toregister with their local authority under the Environmental Protection Act 1990. This Guide will alsohelp companies that are registered to meet the requirements of their Local Air Pollution Controlupgrade plans cost-effectively.

There is an Action Plan at the end of this Guide to help you focus on the ideas that are most relevantto your company.

The other Guides in the series cover surface preparation, coating materials and applicationtechnology. All are available free of charge through the Environmental Helpline on 0800 585794.

S U M M A R Y

Section Page

1 Introduction 1

2 Solvent use in painting and coating 3

3 What is materials management? 4

3.1 Defining your aims 4

4 Waste minimisation 6

4.1 Identifying waste 7

4.2 Measuring waste 8

4.3 The cost of waste 8

4.4 Taking action 9

4.5 Investigating waste 9

4.6 Measuring to Manage 10

5 Good housekeeping 12

6 Paintshop management 14

6.1 Paintshop layout 14

6.2 Paint delivery systems 14

6.3 Workpiece handling 14

6.4 Process efficiency 15

6.5 Scheduling 16

7 Action plan 17

C O N T E N T S

The four complementary Guides to cost-effective paint and powder coating in this series are:

All four Guides are available free of charge through the Environmental Helpline on 0800 585794.

These Guides are intended to help a range of companies, including:

■ metal finishers;

■ fabricators;

■ component and assembly manufacturers for original equipment manufacturers;

■ original equipment manufacturers.

These Guides are applicable to companies using paints and powders to coat metal in:

■ predominantly manual operations, eg hand-spray booths;

■ partially automated operations;

■ fully automated operations.

Symbols printed at the top of relevant pages or Sections of the Guide are intended to help you finduseful ideas for saving money, time and raw materials.

save money

save time

use less paint and solvent

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Good Practice Guide (GG50) Cost-effective Paint and Powder Coating: MaterialsManagement

Good Practice Guide (GG51) Cost-effective Paint and Powder Coating: SurfacePreparation

Good Practice Guide (GG52) Cost-effective Paint and Powder Coating: Coating Materials

Good Practice Guide (GG53) Cost-effective Paint and Powder Coating: ApplicationTechnology

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Better Practice Leads to Improved Profits

An in-house paintshop had a 17% reject level. This meant that up to five workers at any onetime were needed to strip or sand parts prior to reworking. An external consultant highlightedseveral problems - all relating to the standard of operations and housekeeping.

■ Paint quality was not controlled, with no measurement of viscosity or temperature andtherefore no proper adjustment of spraying parameters.

■ Plant was not maintained, eg spray guns were not serviced unless they stopped workingdue to a blockage, breakage or the failure of ancillary equipment.

■ The person performing quality control (a quick check for pass or fail) was too busy totell the operators when there was a problem. The only feedback was given at the endof each shift.

The consultant analysed process requirements before setting quality standards, writingoperating procedures, training the sprayers and setting up a corrective-action system forcommunicating quality problems and implementing change.

On the consultant’s recommendation, the company employed an additional person to dealspecifically with housekeeping. This person carries out quality control on the paint and plant,maintains equipment, acts as a stand-in if necessary and trains new staff.

Reject levels are now less than 2% and still improving. Production levels have remainedconstant, but sales have increased by 15.5%. Only one person is now needed to preparerejects for processing and material costs have also fallen significantly. Profits are thereforenearly 30% higher, even after allowing for the small increase in staff costs.

Organic solvents are widely used in UK industry for a range of processes. Typically, the metal coatingindustry uses trichloroethylene, xylene, methyl ethyl ketone (MEK) and white spirit, mainly in paintsand for cleaning and thinning processes.

These, and other organic solvents, give rise to volatile organic compound (VOC) vapours. Currently,levels of these VOCs in the atmosphere are a subject of widespread concern and regulation. This isprimarily because of their role in the formation of low-level air pollution affecting human health,crops and natural vegetation, but also because they contribute to global warming.

Recent legislation, eg the Environmental Protection Act (EPA) 1990 and its associated regulations,places strict controls on VOC emissions from industry.

Under the provisions of Part I of the EPA 1990, metal coating companies that use more than fivetonnes of solvent a year are required to register with their local authority for an authorisation tooperate. Under Local Air Pollution Control (LAPC), authorisations are granted by local authoritiesprovided companies comply with the requirements of the relevant Secretary of State’s ProcessGuidance Notes. Advice about LAPC and other legislation governing your operation is availablefrom the Environmental Helpline on 0800 585794.

Even if your company does not use enough solvent to be regulated under the EPA 1990, using goodpractice will still enable you to achieve significant cost savings. Companies approaching theregistration threshold may also be able to postpone or avoid registration.

Improving the way in which you manage your material use, as described in this Good Practice Guide,will help to:

■ reduce costs;

■ reduce VOC emissions;

■ meet LAPC upgrade plans (if applicable).

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Materials management is the process of understanding and controlling the use of materials withina company. Although this Guide refers primarily to solvents and solvent management, thetechniques can be applied to any material used by industry.

Good materials management will help your company improve the control of its paint and solventconsumption. Use materials management if your company wants to:

■ reduce paintshop costs and thus increase profits;

■ increase paintshop capacity while avoiding capital investment;

■ reduce solvent consumption to:

– a level that does not require registration under the EPA 1990, thus reducing costs andmanagement time spent on non-core business;

– meet LAPC upgrade plans.

Your company may also wish to:

■ reduce employees’ potential exposure to solvent vapours;

■ reduce the impact of its operations on the local environment.

This Guide describes ways in which you and your company can meet these aims. However, selectingone or more of these ideas may only move your company part of the way towards its objectives. Tobenefit from materials management, your company needs to adopt a systematic approach. This isachieved by:

■ defining your company’s aims in managing its material use;

■ assessing how your company’s performance matches up to these aims;

■ deciding how your company can progress towards meeting these aims.

3.1 DEFINING YOUR AIMS

At the beginning of the process of improvement, a company needs to define its aims.

■ Costs are universally important - few companies will turn down the opportunity to savemoney and boost profits. Reducing costs will also help your company remain competitive.

■ Increasing paintshop or production capacity may be important to a growing company,especially if it is reaching its current capacity.

■ Avoiding or postponing the need to register under LAPC will enable a company to save thecosts of authorisation. These include not only the application fee and annual charge, but alsothe costs involved in collating and submitting solvent inventories, and writing andimplementing upgrade programmes.

■ Improved solvent management may give the added bonus of allowing increased capacitywithout the need for registration under LAPC. Small, but growing, companies currentlyunder the threshold for registration may want to postpone registration for as long as possible.

■ Companies registered under LAPC will want to use the most cost-effective route tocompliance with upgrade plans and other conditions.

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W H AT I S M AT E R I A L SM A N A G E M E N T ?

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Some companies may have other aims. These aims need to be thought about, discussed, agreed bycompany management and recorded. Having defined its aims and obtained managementcommitment, the company should then consider how to achieve them. One of the best ways ofachieving a reduction in material use is to apply the ‘waste minimisation’ technique, as described inthe following Section.

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Waste minimisation is a systematic approach to minimising the production of waste at source. Inthis sense, ‘waste’ is not just discarded solid materials, but wasted time, loss of materials to air anddrain, and excessive use of energy and water. All of these cost money. Rather than creating waste,and then perhaps having to pay for it to be taken away, why not aim to stop producing italtogether?

In practice, it is not always possible to stop generating waste completely. However, it may bepossible to reduce the amount of waste a company produces. Alternatively there may be ways ofputting waste to good use through re-use or recycling (in-house or externally). Finally, a companymay have to consider treating its waste to make it less harmful to people and the environment. Fig 1 summarises this ‘waste management hierarchy’.

Three other Good Practice Guides published by the Environmental Technology Best PracticeProgramme may help your company organise and implement a waste minimisation programme.These Guides, which are available free through the Environmental Helpline on 0800 585794, are:

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Good Practice Guide (GG25) Saving Money Through Waste Minimisation: Raw MaterialUse

Good Practice Guide (GG26) Saving Money Through Waste Minimisation: Reducing WaterUse

Good Practice Guide (GG27) Saving Money Through Waste Minimisation: Teams andChampions

Fig 1 Waste management hierarchy

BEST

Minimise

Re-use

Recycle in-house

Recycle off-site

Treat

4.1 IDENTIFYING WASTE

Waste minimisation requires a company to take a systematic look at all the waste its operationsgenerate - not just solvent use, although this may be a good starting point. The first thing to do isto identify all the forms of waste generated within the company.

The list might include obvious wastes such as:

■ waste paint;

■ waste gunwash solvent;

■ waste cleaning solvent;

■ waste paint containers;

■ dry wastes eg rags, wipes and abrasives.

The list can also include less obvious wastes such as:

■ gunwash solvent lost to the extraction system during gunwashing;

■ paint lost due to overspray;

■ solvent lost from paint during paint application;

■ time lost due to poor finish quality (rectification/rework).

These wastes need to be identified. Some are easy to find, eg in skips, bins, or drums full of waste.Others are more difficult to pinpoint.

Having identified all possible sources of waste from an operation, the next stage in wasteminimisation involves identifying opportunities to eliminate or minimise different waste streams.These opportunities should be ranked in order of importance, eg safety, cost, environmentalbenefits. The highest priority opportunities can then be implemented in order and the benefitsrealised.

Prioritising action to eliminate or reduce waste is not always easy. While it may seem obvious totackle the biggest waste stream first, companies should consider their aims. Is the priority highestcost or biggest waste of material?

This type of structured approach to waste minimisation is best carried out by teams, as this spreadsthe workload and helps to keep a balanced view. Having team members from various functions anddepartments within the company helps to ensure that:

■ all possible sources of waste are identified;

■ the best solutions to problems are generated.

If possible, team members should be selected from all levels in the company, ie from the shop floorto senior management. In manufacturing industry, experience has shown that teams are mosteffective if they include employees from:

■ engineering/utilities/site services responsible for the design, installation and maintenance ofplant and equipment;

■ production management responsible for scheduling and line management;

■ operatives who actually perform the day-to-day production tasks and who usually know mostabout activities that cause waste.

Good Practice Guide (GG27) Saving Money Through Waste Minimisation: Teams and Championsgives advice to companies organising a team approach to waste minimisation.

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4.2 MEASURING WASTE

The next stage in waste minimisation is to quantify the wastes that have been identified.

Some wastes are easily measured. Wastes in skips and bins, eg paint cans or waste solvents, can becounted or weighed.

Other wastes such as rework or wasted time are not as easy to measure. Timesheets, productionlogs and batch records are good sources of information about rework rates. However, these sourcesof information may be of poor quality - you may need to set up systems to collect good quality,reliable data.

Estimating the amount of paint and solvent used each year and comparing these figures with yourwaste disposal records can sometimes highlight areas of significant waste. If your company isregistered under LAPC, you will already need to keep a detailed solvent inventory and submit recordsto your local authority as part of your authorisation to operate.

■ Ask your solvent supplier for details of your solvent purchases and for advice on how to workout your solvent losses.

■ Ask your paint supplier for details of paint purchases and how much solvent your rawmaterials contain.

■ Ask the waste disposal companies you use to confirm your waste disposal records.

Good Practice Guide (GG13) Cost-effective Solvent Management describes how to keep track ofsolvent use. This Guide is available free through the Environmental Helpline on 0800 585794.

4.3 THE COST OF WASTE

Does your company know exactly how much its waste is costing? Experience has shown that mostcompanies significantly underestimate this amount.

As wastes are measured, so costs can be assigned to them. It is important to know the costs of:

■ waste disposal;

■ useful material that is being thrown away in error or wasted through rework.

Information about material costs is usually known by someone within a company, but not often byeveryone. For example, if sprayers are made aware of the cost of paints and solvents, then they willbe more aware of the cost of any wastage.

Rework costs should also be determined. These include:

■ the cost of the additional coating materials;

■ the cost of the materials to clean the job for rework;

■ the cost of the labour required to do the rework.

At the end of this exercise, your company should have a reasonable idea of which wastes are costingthe most.

This is the point at which you can take action to reduce waste.

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4.4 TAKING ACTION

Some ways to reduce waste will be obvious. Some of the ideas from this and other Guides producedby the Environmental Technology Best Practice Programme may be useful, eg Good Practice Guide(GG28) Good Housekeeping Measures for Solvents, and (ET30) Finding Hidden Profit - 200 Tips forReducing Waste. You may want to develop your own ideas, particularly those specific to yourcompany’s operations.

However, it is important to ensure that any action taken to reduce or eliminate waste is cost-effective.

For example, your company may decide that one priority is to reduce the disposal costs for wastesolvent. One possibility is to buy a solvent distillation machine and recover solvent in-house. Thepayback on the investment can be easily calculated by dividing the purchase cost by the annualsavings. These consist of the money saved by not sending the solvent waste for disposal plus themoney saved on solvent purchases, less the annual operating costs.

Projects with paybacks of less than a year will be self-financing as they can be carried out withoutaffecting your budget. In addition to cost savings, waste minimisation opportunities can alsoprovide:

■ improved quality;

■ increased plant capacity;

■ improved health and safety;

■ lower environmental emissions.

Agreeing the actions to take in other priority areas may be more difficult. You may have identifiedthe problem but you don’t know what’s causing it. In such cases, investigations will be needed toidentify possible causes. However, action to discover the reason for waste should be taken only ifthe waste in question is significant.

For example, a company may decide that the cost of purchasing and disposing of solvent used forspray gun washing is a priority area for waste minimisation. The problem is that nobody knowswhere all the solvent goes. The obvious solution is to find out how the gunwash solvent is used andwhere it might be wasted.

Good Practice Guide (GG25) Saving Money Through Waste Minimisation: Raw Material Usedescribes how to gather all the data and information needed to identify opportunities for reducingwaste and how to prioritise these ideas.

4.5 INVESTIGATING WASTE

There are a number of practical ways of identifying waste and its causes (see also the IndustryExample in Section 5). For example you can:

■ observe how people operate and use materials;

■ compare the different ways people operate;

■ ask people where they think materials could be saved.

In larger plant, it may be necessary to compare the performance of machines or production linesagainst each other and against their specifications.

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When talking to people about waste, it is important to explain what the aim of the wasteminimisation programme is. Stress that the company is trying to save money, not trying tofind out whose fault the waste is.

Consider instituting a ‘no-blame’ system or at least be aware that instilling a ‘blame culture’ candrive waste and rework underground. This benefits nobody.

It is also important to remember that there is often more than one correct way to do a job - butthere will always be one way that is more efficient, ie lower cost, than the rest.

It may prove more difficult to identify the cause of a particular waste. This is where a techniqueknown as ‘Measuring to Manage’ can help.

4.6 MEASURING TO MANAGE

To reduce material use or costs a company needs to be in control of the job in hand. But a companycannot manage something if it is not being measured in the first place. Measuring to Manage is allabout getting and keeping control over the use of solvent, paint, energy, etc by measuring it andthen comparing that measurement against how it was used.

For example, when filling a car with petrol, many people keep a note of their car’s mileage and howmuch petrol was needed to refill the tank. They can then calculate the distance travelled againstthe fuel consumed and work out the miles/gallon (or kms/litre) and check it is what they wouldnormally expect.

You learn through experience that when the fuel consumption goes up the car probably needs aservice. If the fuel consumption changes suddenly, then you know there is something wrong withthe car and can investigate the problem. Seeing whether the fuel consumption returns to normalis one way of checking you have found the right solution.

Similar techniques can be used in industry. By measuring the quantity of material (solvent or paint)or energy used and comparing this figure with a measure of work, you can start to get a feel forwhat the average use is and how much it varies. Possible measures of work include:

■ items coated;

■ area of paint applied;

■ number of spray guns cleaned.

Weekly measurement and comparison is recommended. Taking measurements every day is time-consuming, while with monthly measurement people tend to forget what happened earlier in themonth, making it difficult to achieve control.

It is often useful when Measuring to Manage to record the ratio of consumption to production.Examples of the many possibilities include:

■ gunwash used in a week/number of spray guns washed;

■ gunwash used in a week/number of jobs coated;

■ gunwash used in a week/area of paint applied;

■ quantity of paint used/area of paint applied;

■ quantity of paint used/number of items coated.

A good way of presenting this information is to draw a graph. Pictures can often tell you far morethan numbers on a page can.

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4.6.1 Presenting data

You can use your data to plot a scatter graph (sometimes known as a ‘cost driver chart’) like the oneshown in Fig 2.

The line of ‘best fit’ represents the average amount of solvent used each week to wash a givennumber of guns. You can use this line to predict how much solvent you might need forgunwashing. You can also use the line to identify weeks when you have done better or worse thanstandard (or average). Points above the line are worse, points below are better. Minor variations inmaterial use are to be expected and should be tolerated.

You can now start to work towards improved use of materials by finding out how or why you dobetter or worse than standard each week. As you find out the answers, you must take action toprevent repeating events that cause worse performance. You must also ensure that betterperformance is encouraged and repeated.

If you identify and eliminate the causes of waste, you will see, with time, all your measurementsfalling below the line. You will also start to see costs falling.

Good Practice Guide (GG25) Saving Money Through Waste Minimisation: Raw Material Use givesmore practical advice on taking measurements, drawing graphs and presenting information.

Measuring to Manage can also help companies to monitor medium-term and long-term trends inmaterial use. This enhances business control, planning and predictability.

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Fig 2 Example scatter graph of measured performance

Remember:

If you don’t measure it, you can’t manage it.

Solv

ent

use

d/w

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Number of guns washed per week

The line of 'best fit'

Worse than average

Better than average

One easy and low-cost way of reducing waste is to improve your company’s housekeeping. Thismeans stopping the casual waste of materials and energy which occurs through bad habits, poorpractices and use of unsuitable equipment.

It is estimated that UK industry wastes up to 10% of materials through poorhousekeeping.

Good housekeeping measures, which often cost nothing to implement, include:

■ putting caps back on solvent cans and drums;

■ putting lids on paint cans;

■ storing paint cans and solvent cans/drums so they cannot get knocked over;

■ closing tank lids and keeping them closed;

■ ensuring that cans are fully emptied into the solvent waste before throwing them into a solidwaste skip;

■ setting up stock rotation systems to ensure that paints do not go out of date;

■ enclosing paint mixing scales in sealed plastic bags to prevent spillages from causing weighinginaccuracies and potential damage;

■ only mixing or measuring out sufficient paint for the job;

■ in larger installations, fixing leaks in solvent and paint distribution pipework immediately.

Your company can also set housekeeping standards. It is important to:

■ write down a list of rules that are expected to be kept (an example is shown in Fig 3);

■ make sure everyone in the company knows what these rules are and understands the reasonsfor them.

Fig 3 Good housekeeping rules

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put caps back on so lvent cans and drums

put l ids on paint cans

store paint and so lvent cans and drums so they cannot get knocked over

c lose tank l ids and keepthem c losed

make sure cans are fu l ly empt ied into the so lvent waste before throwing them into a so l id waste sk ip

remember s tock rotat ion

only mix suff i c ient paint for the job

Green & Keen Ltd Housekeeping Standards

To reinforce the rules, carry out regular - perhaps weekly - housekeeping reviews by walking aroundthe factory or paintshop looking at how clean and tidy things are.

■ Look for spills, tops off cans, solvent rags left lying around, etc.

■ Ask people to correct faults straight away.

■ Congratulate people who are doing things correctly or when the factory/paintshop is cleanand tidy.

■ Explain to people that keeping high standards of housekeeping will improve workingconditions and reduce costs.

To keep everyone involved, you could consider posting a housekeeping review report on a notice-board so that everyone in the company knows how they are doing. This approach can also be usefulin instilling an element of competition between departments or shifts.

Good Practice Guide (GG28) Good Housekeeping Measures for Solvents describes practical andaffordable measures for reducing solvent and paint losses, together with ways of reducing the riskof pollution from handling and storing such materials.

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The Rewards of Good Housekeeping

A number of problem areas were highlighted when a company operating an automaticpowder plant with manual touch-in took stock of its operations. For example, it found that:

■ colour changes were slow owing to a lack of procedures and the wide range of coloursused;

■ the right powder was never available when needed;

■ half the staff stood around at the beginning and end of the day waiting for componentsto be pre-treated or unloaded after stoving;

■ the plant was dirty, leading to contamination of finished components;

■ quality standards varied due to the lack of information given to operators.

Significant increases in productivity, sales and profits were achieved by introducing goodhousekeeping measures, eg:

■ a person was employed to keep the factory clean and to perform general duties such asfetching powder and disposing of old boxes;

■ a production system that includes a card stipulating requirements which follows the jobaround the plant;

■ a planned production schedule based on colour, ease of colour change, customerdelivery time and plant hour requirements;

■ training of operators and the introduction of written procedures reduced downtimeparticularly on colour change.

Production has increased by 6%, while profits have increased by over 10%. Downtime is 4 - 6 hours/week less, quality standards have improved due to the new production system andthe cleaner, more organised environment has improved employee motivation.

Paintshop design and layout can have a marked effect on both the efficiency and capacity of yourpaintshop operation.

6.1 PAINTSHOP LAYOUT

Paintshop layout depends on:

■ the space available;

■ the location of the paint store in relation to spraying operations.

Each stage of a painting/coating process should be examined to determine its layout requirements.

Due to the flammable nature of solvent-based paints, paint stores are usually located away from themain production building, often in prefabricated sheds with little or no space heating.

Paint becomes more viscous when cold. This can lead to too much thinner being added to producethe desired spraying viscosity, which in turn leads to a dilute coating being applied.

The use of paint lockers containing smaller amounts of paint located next to spraying areas allowsgreater control of paint temperature and more even application throughout the year. Storing theday’s materials at hand also saves time.

6.2 PAINT DELIVERY SYSTEMS

Using pumped or pressurised paint pots also improves the efficiency of paint handling. Such paintpots can hold and deliver larger amounts of paint than a standard spray cup, thus saving time onrefilling. However, they are really useful only when single colours are being sprayed.

In contrast to pressurised systems, pumped systems can be quickly topped up to prime the systemonce spraying has begun.

Paint pots can, if necessary, be stored in a temperature-controlled environment to provide greatercontrol over viscosity.

Pumped ring mains, where paint is distributed from a paint store to numerous spray guns, are oneof the more sophisticated paint delivery systems available to medium-to-high volume users. Somesystems have built-in paint heating to control viscosity, while others allow different colours or painttypes (primer, basecoat, clearcoat, etc) to circulate separately within the system at the same time.The latter have spray guns equipped for quick changeovers.

6.3 WORKPIECE HANDLING

Workpiece handling should also be considered when designing a paintshop.

Cleaning requirements should be taken into account in jig design. For example, the useful life ofjigs can be prolonged by:

■ having a minimal surface area to prevent build-up of overspray;

■ fitting caps to cover unused hangers.

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6.3.1 Smaller operations

The use of hooks to hang workpieces from when spraying, or a wheeled A-frame for largerworkpieces, enables a sprayer to reach all sides easily. This allows spraying to be carried out in oneoperation. The next workpieces can then be loaded onto a second frame while those already coatedare flashing off.

6.3.2 Larger operations

The use of a conveyorised transport system using jigs or flight bars should be considered when largenumbers of workpieces are passing through a painting process.

Where jigs are used with electrostatic application systems, it is important to ensure that the partsare adequately earthed so that:

■ spraying efficiency is maintained;

■ a charge does not accumulate and pose a fire risk.

Connection to earth can be achieved by:

■ designing the jig to be self-seating, ie the component always rests on the same point(s), thuspreventing these points being insulated by applied coating;

■ ensuring that the jig is in contact with a part of the component which does not get coated.

Where jigs are used for dipping components, they should be designed to reduce paint drag-out toa minimum to reduce losses.

6.4 PROCESS EFFICIENCY

Conveyorised systems require sequential ordering of the process. Where processes have beenextended in an ad hoc manner, double handling of components can often be reduced bymodifications to the plant layout. This will:

■ save time;

■ minimise damage due to mishandling;

■ reduce production bottle-necks.

Remember, output rates are dictated by the slowest stage of the production process. Bottle-necksneed to be identified and eliminated. For example, if stoving is the slowest part of the process,installing a bank of infrared driers prior to an existing oven could enable the entire line to run morequickly, thus increasing effective capacity.

Jig or flight bar design also affects the plant’s capacity. For example, if a conveyor is moving at fourmetres/minute, then four metres of conveyor space are available every minute. However, theeffective width of the spray operation dictates the area available for spraying. This is the limitingfactor, not the conveyor speed. The greater the density of workpieces on the line, the greater theoutput.

If, for example, you are coating small workpieces using hangers set one metre apart, then usingsecondary hangers holding several workpieces will enable you to increase capacity. It could alsomean that the line can be loaded and unloaded more quickly.

Process set-up is often time-consuming and reduces coating plant capacity, eg colour changes mayrequire guns, lines and paint vessels to be cleaned. Anything which reduces the time taken to setup a process will speed up the changeover process and increase output.

Preparatory tasks that can be carried out while the plant is operating will reduce changeover times.

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6.5 SCHEDULING

Scheduling of workloads can reduce significantly the amount of time and materials used for settingup and cleaning equipment.

Scheduling light-to-dark production every day or shift could enable guns and paint pots to be usedwithout being cleaned as the darker colours may mask the lighter ones. Although the quality of thefinal finish may be paramount, there are cases where this technique has advantages.

Where a variety of different finishes is used, scheduling large batches of similarly coated objectstogether - rather than interspersing them - reduces time and materials losses due to cleaning andset-up. The people in charge of scheduling should be aware of these technical issues and bear themin mind, rather than just dealing with the needs of customers.

By discussing these technical issues with schedulers and customers, it may be possible to producelarger batches of goods less frequently. Some of the cost saving could be passed on to thecustomer. Just-In-Time production requirements may, however, preclude this option.

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A C T I O N P L A N7

IF YOU WANT TO:

Reduce paint and solvent consumption

Use materials management to control your paint and solvent use.

Follow a structured approach to waste minimisation:

– identify and quantify wastes;

– work out how much waste is costing your company;

– investigate significant sources of waste;

– take action to reduce waste according to your company’s priorities.

Control materials and energy use by Measuring to Manage.

Implement a good housekeeping programme.

Consider your paintshop management:

– optimise paintshop design and layout;

– improve paint handling and process efficiency;

– consider workload scheduling when handling large numbers of workpieces.

Contact the Environmental Helpline on 0800 585794 to obtain free copies of theEnvironmental Technology Best Practice Programme publications mentioned in thisGuide.

Don’t forget to ask for the three other Good Practice Guides in the series on cost-effective paint and powder coating, if they relate to your operation.

Good Practice Guide (GG51) Cost-effective Paint and Powder Coating: SurfacePreparation

Good Practice Guide (GG52) Cost-effective Paint and Powder Coating: CoatingMaterials

Good Practice Guide (GG53) Cost-effective Paint and Powder Coating:Application Technology

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A V I N G S

COST

The Environmental Technology Best Practice Programme is a joint Department of Trade and

Industry and Department of the Environment initiative. It is managed by AEA Technology plc

through ETSU and the National Environmental Technology Centre.

The Programme offers free advice and information for UK businesses and promotes

environmental practices that:

■ increase profits for UK industry and commerce;

■ reduce waste and pollution at source.

To find out more about the Programme please call the Environmental Helpline on freephone

0800 585794. As well as giving information about the Programme, the Helpline has access to

a wide range of environmental information. It offers free advice to UK businesses on technical

matters, environmental legislation, conferences and promotional seminars. For smaller

companies, a free counselling service may be offered at the discretion of the Helpline Manager.

FOR FURTHER INFORMATION, PLEASE CONTACT THE ENVIRONMENTAL HELPLINE

0800 585794e-mail address: etbppenvhelp@aeat.co.uk

World wide web: http://www.etsu.com/ETBPP/