A coating factory is a place where films are formed on products.

It applies and dries coating materials to create films with appearance, rust protection, durability, and functionality.
In this sense, coating is an important process that increases product value.

However, a broader view of a coating factory reveals another aspect.

It consumes many resources, including coating materials, thinners, surface preparation chemicals, water, electricity, gas, compressed air, filters, wiping cloths, and masking materials.

While coated products are produced, waste coating material, waste thinner, VOCs, wastewater, sludge, used filters, empty cans, odors, heat, and noise are also generated.

Coating factories must therefore be viewed through INPUT and OUTPUT.

What is put in?
What becomes product value?
What leaves as waste or environmental burden?

This perspective is the basis of waste reduction.

1. What are a coating factory’s INPUTs?

Many things are put into a coating factory.

Typical INPUTs are as follows.

• Workpieces
• Coating material
• Thinner
• Curing agents
• Surface preparation chemicals
• Cleaning agent
• Water
• Electricity
• Gas and fuel
• Compressed air
• Filters
• Wiping cloths
• Masking materials
• Jigs
• Carts
• Working time
• Operator effort

Only some of these ultimately remain as product value.

Some coating material becomes the film.
Surface preparation chemicals are used to prepare the surface.
Electricity and gas operate booths, drying ovens, compressors, lighting, and other equipment.
Water is used for cleaning and surface preparation.

However, not everything becomes product value.

Some coating material becomes overspray.
Some thinner evaporates.
Thinner used for cleaning becomes waste thinner.
Surface preparation baths become waste liquid when replaced.
Filters and wiping cloths become waste after use.

Examining INPUT means examining how purchased materials and energy are used.

2. What are a coating factory’s OUTPUTs?

A coating factory’s OUTPUT is not limited to coated products.

Product OUTPUT consists of coated parts or products.
However, many other discharges are generated at the same time.

Typical OUTPUTs are as follows.

• Coated products
• Waste coating material
• Waste thinner
• Waste cleaning liquid
• Exhaust containing VOCs
• Odors
• Waste surface preparation liquid
• Wastewater
• Wastewater treatment sludge
• Booth sludge
• Coating residues
• Used filters
• Dirty wiping cloths
• Used masking materials
• Empty cans
• Waste plastic
• Waste heat
• Noise

Of these, coated products are shipped with value.
Most of the others require treatment, storage, recovery, or management.

Waste is therefore not simply something that inevitably appears. It is part of the INPUT leaving without becoming product value.

Examining OUTPUT alone is insufficient for waste reduction.
It is necessary to trace why that OUTPUT arose back to the INPUT and process.

3. Waste was originally purchased material

Waste coating material, waste thinner, sludge, used filters, and empty cans
are treated as waste on the shop floor.

Viewed differently, however, they were originally purchased materials.

Waste coating material was originally coating material.
Waste thinner was originally thinner.
Sludge was originally coating material or surface preparation constituents.
Used filters were originally purchased auxiliary materials.
Empty cans are containers generated each time coating material is purchased.

A large amount of waste therefore means that purchased materials fail to become product value and leave the factory with additional treatment costs.

This is both an environmental issue and a production cost issue.

Reducing waste does more than reduce environmental burden.
It also reduces material costs, treatment costs, storage space, working time, and management burden.

4. Waste reduction should not begin with treatment after generation

Waste measures tend to bring disposal contractors, storage locations, separation, and regulatory compliance to mind.

These are, of course, important.
Waste must be stored and treated appropriately in accordance with laws and company rules.

However, waste reduction as process improvement should not begin with treatment after generation.

The first thing to examine is the source.

Where is waste coating material generated?
Where is waste thinner increasing?
Which color changes require substantial cleaning?
Which products have excessive film thickness?
Which booths produce substantial sludge?
Which processes require frequent filter replacement?
Which coating materials remain unused?

Improving treatment alone without examining sources will not reduce waste.

Waste reduction must begin with preventing generation rather than with treatment.

5. Reduce comes first in the 3Rs

Waste reduction uses the concept of the 3Rs.

Reduce: Reduce the amount generated.
Reuse: Use materials again.
Recycle: Recover materials as resources.

All three are important.

However, the first priority in a coating factory is Reduce:
reducing the amount of waste generated.

Examples include the following improvements.

• Do not mix more coating material than needed.
• Reduce excessive film thickness.
• Improve transfer efficiency.
• Reduce the number of color changes.
• Reduce cleaning thinner consumption.
• Reduce recoating of defective products.
• Optimize filter replacement.
• Stabilize surface preparation bath control.
• Reduce expired coating materials.

Reuse and Recycle are also important, but a treatment burden remains if generation is high.

First, prevent generation.
Next, reuse.
Recycle what still remains.
Finally, treat it appropriately.

This order is important.

6. Examine coating material losses

Coating material losses are important in reducing coating factory waste.

Not all coating material used attaches to the product.
In spray coating, material that does not attach travels toward the booth.

These losses appear in the following forms.

• Overspray
• Booth mist
• Deposits on filters
• Booth sludge
• Coating residues
• Deposits on floors or jigs
• Leftover coating material
• Waste coating material

High coating material losses increase purchasing costs.
Waste treatment costs also increase.
Booth cleaning and filter replacement become more frequent.

Reducing coating material losses requires considering the following points.

• What is the transfer efficiency?
• Is spray distance appropriate?
• Is air pressure appropriate?
• Is film thickness excessive?
• Does the coating method suit the workpiece shape?
• Are the jigs and hanging arrangements appropriate?
• Are automatic coating conditions correct?
• Are there differences between operators?

Coating material losses are both an environmental issue and a production cost issue.

7. Examine thinner losses

Thinner consumption is also important in factories using solvent-based coatings.

Thinner is used for dilution, viscosity adjustment, washing, and cleaning.
However, improper use increases waste thinner.

Examples include the following conditions.

• Thinning ratios differ between operators.
• More thinner than necessary is added.
• Large amounts of cleaning thinner are used at every color change.
• Cleaning thinner is not reused in stages.
• Clean and dirty thinner are not separated.
• Waste thinner quantities are not known by process.
• Cleaning methods are not standardized.

Thinner becomes VOCs when it evaporates.
After cleaning, it becomes waste thinner.
Both cause environmental burden and costs.

Reducing thinner losses requires reviewing thinning control, cleaning methods, color change sequences, and waste thinner separation.

8. Examine surface preparation and wastewater

Surface preparation also generates OUTPUTs in coating factories.

Degreasing.
Water rinsing.
Conversion treatment.
Surface conditioning.
Pickling.
Chemical treatment.

These processes use water and chemicals.
They consequently generate wastewater, waste liquid, sludge, and treatment sludge.

Unstable surface preparation control may increase waste and wastewater loads.

Examples include the following conditions.

• Chemical concentration is unstable.
• Rinse water is poorly controlled.
• Oil carry-in is high.
• Bath replacement is frequent.
• Sludge generation is high.
• Wastewater treatment load is large.
• Surface preparation defects require reprocessing.

Surface preparation OUTPUTs affect coating quality as well as environmental measures.
Unstable surface preparation causes poor adhesion, rust, blistering, and other problems.

The INPUTs of chemicals, water, and energy must be examined together with the OUTPUTs of wastewater, sludge, and defects.

9. Examine energy OUTPUTs as well

Coating factory INPUTs are more than materials.
Energy such as electricity, gas, and compressed air is also important.

Not all heat supplied to the drying oven is used to dry the coating film.
Some escapes through the oven body.
Some leaves with the exhaust.
Some heats jigs and carts.
It also contributes to a hot workplace.

Not all compressed air produced by the compressor is used effectively either.
Air leaks.
Excessive air blowing.
Supply to unused equipment.
Higher pressure than necessary.

These are energy losses.

Energy OUTPUTs include waste heat, noise, air leaks, and excessive exhaust.

A broad approach to coating factory waste reduction must examine energy losses as well as material losses.

10. Examine INPUT and OUTPUT by process

Examining INPUT and OUTPUT for the entire factory is important.
However, looking only at the whole factory makes causes difficult to identify.

Examining them by process is therefore effective.

Surface preparation process

INPUT: Water, chemicals, electricity, and heat.
OUTPUT: Wastewater, waste liquid, sludge, and treatment sludge.

Mixing process

INPUT: Coating materials, curing agents, thinners, containers, and wiping cloths.
OUTPUT: Leftover coating material, empty cans, dirty wiping cloths, and waste coating material.

Coating process

INPUT: Coating materials, thinners, compressed air, electricity, and filters.
OUTPUT: Coated workpieces, overspray, mist, waste filters, and booth sludge.

Cleaning process

INPUT: Cleaning thinner, wiping cloths, and working time.
OUTPUT: Waste thinner, dirty wiping cloths, odors, and VOCs.

Drying process

INPUT: Electricity, gas, heat, and exhaust airflow.
OUTPUT: Dried coating films, VOC exhaust, waste heat, and odors.

Inspection and repair process

INPUT: Working time, repair coating materials, and thinner.
OUTPUT: Repaired products, recoated products, defective products, and additional waste.

Examining each process makes opportunities for improvement easier to identify.

11. Waste reduction is also linked to quality improvement

Waste reduction is not solely the environmental department’s work.

It is also closely linked to quality improvement.

Fewer defective products mean less recoating.
Less recoating means lower coating material consumption.
Cleaning thinner consumption also decreases.
Drying oven operating time decreases.
Waste coating material and waste thinner also decrease.

Quality defects therefore increase waste.

For example, frequent contamination defects increase repairs and recoating.
Frequent film thickness defects increase coating material losses and rework.
Color mismatches may even cause the entire product to be discarded.
Insufficient drying may require drying again or recoating.

Reducing defects is particularly important for waste reduction.

Environmental measures and quality improvement are not separate activities.
They are linked within the same process improvement effort.

12. CoatureVietnam’s approach to INPUT and OUTPUT diagnosis

CoatureVietnam emphasizes INPUT and OUTPUT when diagnosing a coating factory.

It checks items such as the following.

INPUT

• Coating material consumption
• Thinner consumption
• Surface preparation chemical consumption
• Water consumption
• Electricity consumption
• Gas and fuel consumption
• Compressed air consumption
• Filter, wiping cloth, and masking material consumption

PROCESS

• Mixing
• Thinning
• Coating
• Cleaning
• Drying
• Surface preparation
• Inspection
• Repair
• Rework

OUTPUT

• Waste coating material
• Waste thinner
• VOC exhaust
• Wastewater
• Sludge
• Used filters
• Dirty wiping cloths
• Empty cans
• Defective products
• Waste heat
• Odors

Examining these three together reveals losses in the coating factory.

Which INPUTs are high?
Which PROCESS produces losses?
Which OUTPUTs are increasing?
Can those OUTPUTs be reduced?
Can anything be reused or recycled?
Can generation itself be reduced?

These questions are the starting point for waste reduction.

Conclusion

A coating factory is a process that creates coating films.
At the same time, it consumes materials, water, air, and energy and generates waste, exhaust, wastewater, and waste heat.

This is why it must be viewed through INPUT and OUTPUT.

What is put in?
What becomes product value?
What leaves as waste?
Which processes generate losses?
Where can generation be reduced?

Waste cannot be reduced merely by treating it after generation.
It is important to examine the source first.

Waste coating material was originally coating material.
Waste thinner was originally thinner.
Sludge and used filters were also originally materials supplied to the process.

Reducing waste is an environmental measure, a cost improvement, and a quality improvement.

CoatureVietnam reviews coating factories through INPUT, PROCESS, and OUTPUT.
It considers materials, energy, work, equipment, quality, and waste together and translates the findings into improvements that are easy for the shop floor to implement.

Coating the Future with Science and Care
Reducing waste shows consideration for the global environment while also providing a caring improvement that reduces shop-floor burdens and factory costs.