Guidebook

Raw material

Manufacturing

Converting

Sanding methods

Sanding faults: causes and actions

Product recommendation

1. Raw material1.1 Principles of the construction of coated abrasives

1. Raw material

1.2. Backing material

1.2.1. Paper

1. Raw material

1.2. Backing material

1.2.2. Cloth

1. Raw material

1.3. 1st binder

1.3.1. Animal glue

1. Raw material

1.3. 1st binder

1.3.2. Synthetic resin

1. Raw material

1.4. Grains

1.4.1. Aluminium oxide

1. Raw material

1.4. Grains

1.4.2. Silicon carbide

1. Raw material

1.4. Grains

1.4.3. Grit sizes

1. Raw material

1.4. Grains

1.4.4. Grit sizes

1. Raw material

1. Raw material

1.5. 2nd binder

1.5.1. Synthetic resin

1. Raw material

1.6. Sanding active fillers

1.6.1. Antistatic abrasives

1. Raw material

1.6. Sanding aactive fillers

1.6.2. Stearated abrasives

Raw material

Manufacturing

Converting

Sanding methods

Sanding faults: causes and actions

Product recommendation

2. The manufacturing process

2. The manufacturing process 2.1. Raw material of paper or cloth

Raw material

Manufacturing

Converting

Sanding methods

Sanding faults: causes and actions

Product recommendation

3. Converting3.1. Slitting of rolls

3. Converting3.2. Cutting of material for endless belts

3. Converting3.3. Joint skiving

3. Converting3.4. Joint pressing

Raw material

Manufacturing

Converting

Sanding methods

Sanding faults: causes and actions

Product recommendation

4 Sanding methods

4. Sanding methods 4.1. Calibration4.1.1. Description and recommendations

Calibrate to the right thickness.

Chatter marks from planer, if any, are removed.

Sanding machines equipped with sanding ppads are not suitable for calibration.

The efficiency of the stock removal is effected by the diameter and the hardness of the rollers.

4. Sanding methods 4.1. Calibration4.1.2. Stock removal recommendations

4. Sanding methods 4.2. Cross sanding4.2.1. Description and recommendations

Cross sanding minimizes the ffibre to rise.

Cross sanding facilitates remove veneer tape, glue and filler.

Reduced sanding costs since the cross belt prolongs the life time of the wide belts.

Cross sanding gives a plain surface to the softer and harder parts of the working piece.

4. Sanding methods 4.2. Cross sanding4.2.2. Stock removal recommendations

4. Sanding methods 4.3. Surface sanding4.3.1. Description and recommendations

The required surface must be achieved without large stock removal.

The conveyor belt should have a hardness of approx. 40-50 durometers.

4. Sanding methods 4.3. Surface sanding 4.3.2. Stock removal recommendations

4. Sanding methods 4.4. Lacquer sanding4.4.1. Description and recommendations

Normally a product with grains of silicon carbide is used.

Use as low sanding pressure as possible to reduce friction.

The lacquer must be well cured. When ssanding hard lacquers a product with grains of aluminium oxide is recommended.

4. Sanding methods 4.4. Lacquer sanding4.4.2. Recommendations

4. Sanding methods 4.4. Grit combination

Raw material

Manufacturing

Converting

Surface sanding

Sanding faults: causes and actions

Product recommendations

5. Sanding faults: causes and actions5.1. Chatter marks

Description

Transverse sanding faults on the work piece

5. Sanding faults: causes and actions5.1.a. Chatter marks

5. Sanding faults: causes and actions5.1.b. Chatter marks

5. Sanding faults: causes and actions5.2. Blank lines

Description

Longitudinal, oscillating blank lines, no ridges

5. Sanding faults: causes and actions 5.2.a. Blank lines

5. Sanding faults: causes and actions 55.3. Blank lines

Description

Longitudinal, oscillating short narrow

blank lines, no ridges

5. Sanding faults: causes and actions 5.3.a. Blank lines

5. Sanding faults: causes and actions 5.4. Unbroken ridges

DescriptionLongitudinal, unbroken and narrow oscillating ridges

5. Sanding faults: causes and actions 5.4.a. Unbroken ridges

5. Sanding faults: causes and actions 5.5. Broken ridges

Description

Longitudinal, short and narrow oscillating ridges. Sometimes only following the oscillation in one direction. See the picture

5. Sanding faults: causes and actions 5.5.a. Broken ridges

Causes

1. Too big removal because of to high sanding pressure

2. Too low belt speed

3. Too hard pad

4. Too wide pad

5. Poor dust extraction or poor function of the air jet blower. Sometimes both

Actions

1. Decrease the sanding pressure

2. Increase the belt speed

3. Change to more soft pad

4. Try with a pad there the width is 80-90mm

5. Check the dust extraction and the air jet blower

5. Sanding faults: causes and actions 5.6. Straight short ridges

Description

Longitudinal, 10 – 50mm long and straight ridges.

Mostly appear when you are sanding lacquer

5. Sanding faults: causes and actions 5.6.a. Straight short ridges

Causes

1. Too big removal because of to high sanding pressure

2. Too low belt speed

3. Too low conveyor speed

4. Poor dust extraction or poor function of the air jet blower. Sometimes both

Actions

1. Decrease the sanding pressure

2. Increase the belt speed

3. Increase the conveyor speed

4. Check tthe dust extraction and the air jet blower. Not: With good dust extraction and good cleaning of the belt, generally this type of problem do not appear

5. Sanding faults: Causes and actions 5.7. Straight ridges

Description

Longitudinal, straight ridges. Not oscillating.

This type of sanding fault is created by the sanding machine

5. Sanding faults: Causes and actions 5.7.a. Straight ridges

Causes

1. The contact roller is damaged

2. The graphite is damaged

Actions

1. Resand the roller.

2. By lighter damage: sand the graphite with an abrasive P120. Is the graphite heavily damage change it.

5. Sanding faults: causes and actions 5.8. Scratches

Description

Longitudinal, short oscillating scratches

5. Sanding faults: causes and actions 5.8.a. Scratches

Causes

1. Coarse grains in the sanding belt

2. Impurities in the joints or on the surface of the belt

3. Break marks in the sanding belt

Actions

1. Change the sanding belt

2. Check the joint and the surface of the belt

Change the sanding belt if necessary

3. Change the sanding belt

5. Sanding faults: Causes and actions 5.9. Scratches

Description

Longitudinal, straight scratches. Not oscillating

This type of sanding fault is created by the sanding machine

5. Sanding faults: Causes and actions 5.9.a. Scratches

Causes

1. Foreign particles on pressure beams or pressure rollers

2. Foreign particles on the graphite

3. Foreign particles between the felt and the graphite

Actions

1. Clean the pressure bbeams and the pressure rollers

2. Sand the graphite with an abrasive, P120

2. Clean the felt

5. Sanding faults: Causes and actions5.10. Burning marks

Description

Longitudinal, burning marks

5. Sanding faults: Causes and actions5.10.a. Burning marks

Causes

1. Heavy clogging of the sanding belt

2. Not enough cutting power in the sanding belt, because of to high sanding pressure/ too much removal, (the grains has lost there sharpness)

3. Not enough cutting power in the sanding belt, because of to fine grit

4. Foreign particles between the graphite and the felt. (sanding pad)

5. Raising damage in the contact roller

Actions

1. Change the sanding belt

2. Change the sanding belt

3. Change to a coarser grit

4. Take out the pad unit and clean it

5. Repair the damage

5. Sanding faults: Causes and actions 5.11. Sanding through

Description

The veneer is sanded through in the middle of the work piece

5. Sanding faults: Causes and actions 5.11.a. Sanding through

5. Sanding faults: Causes and actions 5.12. Sanding through

Description

The veneer is sanded through in one side of the work piece

5. Sanding faults: Causes and actions 5.12.a. Sanding through

5. Sanding faults: Causes and actions 5.13. Sanding through

Description

The veneer is sanded through on the left side or on right side of the work piece, or on the both sides

5.

Sanding faults: Causes and actions5.13.a. Sanding through

5. Sanding faults: Causes and actions5.14. Sanding through

Description

The veneer is sanded through on the front edge

5. Sanding faults: Causes and actions5.14.a. Sanding through

5. Sanding faults: Causes and actions5.15. Sanding through

Description

The veneer is sanded through on the back edge

5. Sanding faults: Causes and actions5.15.a. Sanding through

5. Sanding faults: Causes and actions5.16. Sanding through

Description

The veneer is sanded through on the inner edges of the frame detail

5. Sanding faults: Causes and actions5.16.a. Sanding through

5. Sanding faults: Causes and actions5.17. Wavy surface (solid wood)

Description

The surface of the solid wood is uneven, (wavy)

This problem appear especially on soft wood

5. Sanding faults: Causes and actions5.17.a. Wavy surface (solid wood)

5. Sanding faults: Causes and actions 5.18. Sanding through ( lacquer )

Description

The surface of stain and lacquer is sanded through on some parts of the work pieces

5. Sanding faults: Causes and actions 5.18.a. Sanding through ( lacquer )

5. Sanding faults: Causes and actions 5.19. Sanding through ( lacquer ))

Description

The surface of lacquer is sanded through on the left side or on the right side of the work piece, or on the both sides

5. Sanding faults: Causes and actions 5.19.a. Sanding through ( lacquer )

5. Sanding faults: Causes aand actions 5.20. Sanding through ( lacquer )

Description

The surface of lacquer is sanded through on the front edge or on the back edge of the work piece, or on the both edges

5. Sanding faults: Causes and actions 5.20.a. Sanding through ( lacquer )

5. Sanding faults: causes and actions 5.21. Ridges

Description

Longitudinal, 15 – 80mm long and straight ridges.

5. Sanding faults: causes and actions 5.21.a. Ridges

Causes

1. Too big removal because of to high sanding pressure

2. Too low belt speed

3. Lacquer not sufficiently dry

4. Poor function of the air jet blower

5. Poor dust extraction

6. Too low conveyor speed

Actions

1. Decrease the sanding pressure

2. Increase the belt speed

3. Check the drying system

4. Check the air jet blower

4.a Install a 2nd air jet blower for better cleaning of the sanding bbelt

5. Check the dust extraction

6. Increase the conveyor speed

Not: With good dust extraction and strong air jet blower for cleaning of the belt, generally this type of problem do not appear

5. Sanding faults: causes and actions 5.22. The surface is not sufficiently sanded

Description

The surface of lacquer is not sanded even all over the area

5. Sanding faults: causes and actions 5.22.a The surface is not sufficiently sanded

Causes

1. Too low sanding pressure

2. Too low belt speed

3. Too fine grit used

4. The sanding pad iis too hard and not flexible enough

5. The graphite is worn out

Actions

1. Increase the sanding pressure

2. Increase the belt speed

3. Try a coarser grit

4. Use a softer felt or use a mix of felt and foam-rubber

5. Change the graphite

5. Sanding faults: Causes and actions5.23. Folding of the belt

Description

The wide belt usually folding in the middle of the belt

5. Sanding faults: Causes and actions5.23.a Folding of the belt

Causes

1. Too high belt tension. Is usually the primary cause

2. Too high sanding pressure

3. Incorrect oscillation, too fast in one direction or in both directions

4. The belt is not dry

5. Unequal belt tension, (when the machine has two cylinders on each unit for the belt tension)

Actions

1. Decrease the sanding pressure to maximum 4 bar. It is usually enough for all type of wide belt machines

2. Decrease the sanding pressure

3. Store the belt in a dry place

4. Adjust the pressure to equal in both cylinders

5. Sanding faults: Causes and actions5.24. Belt breakage

Description

Belt breakage in the material or joint

5. Sanding faults: Causes and actions5.24.a. Belt breakage

Causes

1. The photocell for the oscillation is not working

2. The photocell is too strong

3. A damage at the edge on the belt has occurred when the belt was changed

4. Improper storage of the sanding belt. They have been conical and run out of tthe

machine

5. The joint is not strong enough, because of a fault in the production

Actions

1. Clean the photocell from dust or change it if not working

2. Adjust the photocell. If it is no possibility to adjust the intensity, cover the photocell with one layer of brown tape

3. Cut away the damage of the edge if it is not more then 10 mm deep. Cut out as half-moon

4. Store the belts in a dry place on wood or board, or hanging on rack

5. Inform the supplier

5. Sanding faults: Causes and actions5.25. Belt flapping

Description

The belt edge is flapping

5. Sanding faults: Causes and actions5.25.a. Belt flapping

Causes

1. Improper storage of the sanding belts

2. High air humidity variations

3. Improperly made joint

Actions

1. Store the belts in a dry place on wood panel or board, or hanging on rack

2. Control the variations of the air humidity in store room and sanding area

3. Inform the supplier

5. Sanding faults: Causes and actions5.26. Cupping

Description

The sanding belts have a tendency of cupping

5. Sanding faults: Causes and actions5.26.a. Cupping

5. Sanding faults: Causes and actions5.27. Irregular belt oscillation

Description

The sanding belt is hard to steer

Causes

Fault within the air cylinder or the photo cell/sensor

Improper storage of the sanding belt. They has been conical

Improperly made joint

Too low belt tension

5. Sanding faults: Causes and aactions5.28. Bad stock removal

Description

The stock removal is too low

Causes

Too low sanding pressure

Too high conveyor speed

Too fine grits are used

The contact roller is too soft

The sanding belts are clogged

5. Sanding faults: Causes and actions5.29. Uneven sanded surfaces

Description

The sanding gives an uneven surface

Causes

Technical error in the pad or a fault in the controlling unit

Dust in the contact elements

Unequal thickness of the working piece

Wrong choice of grits and grit combination

Uneven conveyor speed

5. Sanding faults: Causes and actions5.30. Short life time

Description

The life time of the belt is short

Causes

Too high sanding pressure / too high stock removal

Bad dust extraction system

Bad air jet blower for the belt cleaning

Wrong grit combination

5. Sanding faults: Causes and actions5.31. Dusty machine

Description

The machine gets dusty

Causes

The dust extraction does not work properly

The dust extraction is undersized

High electrical charges

5. Sanding faults: Causes and actions5.32. Poor lacquer adhesion

Description

Poor lacquer adhesion

Causes

Too fine surface

Too fine grits are used

5. Sanding faults: Causes and actions5.33. High consumption of stain or lacquer

Description

Too high consumption of stain or lacquer

Causes

The surface is too coarse

Too low sanding pressure

Wrong grit are used.Use finer grit

Wrong grit combination

Construction and raw material

Manufacturing

Converting

Surface sanding

Sanding faults: causes and actions

Product recommendations

6. Product

recommendations6.1. Wide belt sanding, incl.cross belt.

Sanded products Sanded material Ekamant produkt

Doors Solid wood or veneer PKFO, ARKFO

Table tops Hard wood RKXH

Parquet

Solid wood or veneer PKFO, ARKFO

Soft wood ARKFEO, ARSFEO

RKXH

Plywood Veneer PKFO, ARKFO

Ship board / MDF and Plastic, board, ARSF, ARSFEO laminated panels Corian

All the above Lacquer AESM Filler AESMNS Ground coat

6. Product recommendations 6.2. Long narrow belt sanding (stroke sanders)

Sanded products Sanded material Ekamant product

Table tops Solid wood or veneer PKFO, ARKFO

Hard wood RKXH, RKJ

Solid wood or veneer PKFO, ARKFO

Soft wood ARKFEO

RKXH, RKJ

Ceiling panels Solid wood or veneer PKFO, ARKFO Hard wood

Solid wood or veneer PKFO, ARKFO

Soft wood ARKFEO

RKXH, RKJ

All the above Lacquer AESM Filler AESMNS Ground coat

6. Product recommendations 6.3. Edge sanding

Sanded products Sanded material Ekamant product

Furniture details Hard wood PKFO, ARKFO

RKXH

Soft wood PKFO, ARKFO, ARKFEO

RKXH

Stairs Solid wood or veneer PKFO, ARKFO, ARSFEO

RKXH

6. Product recommendations 6.4. Profile sanding

Sanded products Sanded material Ekamant product

Legs Turned details RKJ, RKJFO

of solid wood

Furniture details Solid wood or veneer RKJ

Big radius

Solid wood or veneer

Small radius RKJFO

Moulding details Solid wood RKJFO

All the above Lacquer RKJFON

Filler

Ground coat