SAAA SAFETY CODE
For the use, care and protection of coated abrasive products
Foreword

Health and safety within the workplace is a "non negotiable" commitment for all responsible organisations. The South African Abrasive Association is further committed to the education of the uses of coated abrasive products to ensure the continued promotion of work place safety

The safety recommendations for the use of Coated Abrasives contained in this publication are only a summary of the most important precaution. All users must strictly follow the safety instructions existing in the laws, decrees and technical standards of South Africa, machine recommendations, and instructions given by the abrasive manufacturer, which are shown on the product backing, labels or blotters.

South African Abrasive Association
P O Box 288
Isando
1600
RSA


This safety code is published by the following participating members.
Ampol Abrasives & Tapes
P O Box 3537
Randburg, 2125
RSA
25 Lyn Road
Ferndale Ext 4
Strijdom Park
Tel: (011) 792-9250
Fax: (011) 792-8106
Email: pa@ampol.co.za
greggc@ampol.co.za
Website: http://www.sia-abrasives.com
Elcarbo Industrial Supplies Gauteng (Pty) Ltd
P. O. Box 2989,
Edenvale,
1610
RSA
86 Dann Rd,
Aston Manor,
1610
Tel: (011) 397-8900
Fax: (011) 397-8953
Email: kevinhill@elcarbo-gt.co.za
admin@elcarbo-gt.co.za
Website: http://www.elcarbo.co.za
Grinding Techniques (Pty) Ltd
PO Box 51
Krugersdorp, 1740
RSA
28 Van Eck Street
Chamdor
Krugersdorp
Tel: (011) 271-6400
Fax: (011) 271-6464
Email: info@grindtech.com
Website: http://www.grindtech.com
Lukas SA (Pty) Ltd
P O Box 800
Germiston, 1400
RSA
1288 Harriet Avenue
Driehoek
Germiston
Tel: (011) 825-1550
Fax: (011) 872-0144
Email: abrasives@lukas.co.za
Website:http://www.lukas.co.za
Pferd-South Africa (Pty) Ltd
P O Box 588
Kempton Park, 1620
RSA
32 Derrick Road
Spartan
Kempton Park
Tel: (011) 230-4000
Fax: (011) 394-1232
Email: info@pferd.co.za
Website: http://www.pferd.co.za
Rebuff (Pty) Ltd
P O Box 752
Isando, 1600
RSA
11 Purlin Street
Isando
Tel: (011) 974-8951
Fax: (011) 974-1930
Email: sales@rebuff.co.za
Website: http://www.rebuff.co.za


CONTENTS
SECTION 1 - Handling and Storage

SECTION 2 - General Precautions and Personal Protection

SECTION 3 - Belts

SECTION 4 - Fibre Discs

SECTION 5 - Flap Discs

SECTION 6 - Paper, cloth and combination discs

SECTION 7 - VELCRO and PSA mounted discs

SECTION 8 - Flap wheels

SECTION 9 - Spindle mounted flap wheels

SECTION 10 - Spirally wound bands and sleeves

SECTION 11 - Orbital/dual action sheets

SECTION 12 - General
(i) Formula examples
(ii) Recommended speeds

Important Notice
Every effort has been made to ensure that all information supplied in this safety code is accurate and up to date at the time of publication. The South African Abrasive Association and its members cannot accept any responsibility for any error or omission, nor for any consequential loss or damage so arising (E & OE).

Copyright Warning
This safety code may contain certain copyright material, which must not be copied or re-used without prior written permission.

SAAA 2003

Safety Code For Coated Abrasives
SECTION 1 Handling and Storage

All coated abrasive products should be handled with care. Mechanical damage can be caused by mishandling which should be avoided .

It is recommended that all coated abrasive products should be stored at constant levels of temperature and humidity within the ranges of 18-22°C, and 45% - 65% Relative Humidity (RH). They should be kept away from damp (or cold) walls, windows or floors to avoid possible moisture absorption. Equally, storage adjacent to heat sources, e.g. steam pipes, radiators, hot air ducts, ovens, etc should be avoided

Coated abrasives should not be exposed to direct sunlight.

Products should be retained in their original packing until immediately prior to use, with the exception of wide belts (see Section 3 paragraph 3.1).

Abrasive rolls should be stored on their side in a single layer (not stacked) to avoid edge damage and to prevent distortion of the centre core.

SECTION 2 General Precautions and Personal Protection

2.1 Selection of the abrasive product
Information on the label of the abrasive product as well as restrictions of use, safety indications or any other instruction should be followed. In case of doubts concerning the selection of abrasive products, the user should request information from the manufacturer or supplier before use.

Recommendations regarding the correct product or system for a particular application may be obtained from any member of the South African Abrasives Association.

2.2 Personal Protection
Personal protection is paramount. The use of safety goggles, ear muffs, safety gloves and dust masks must be enforced and if grinding conditions are severe, additional face protection, leather aprons and safety shoes must be worn. Supervision of all aspects of safety is vital especially eye protection.

It is also strongly recommended that suitable protection be worn against inhalation of airborne particles produced by the grinding process.

Certain coated abrasive utilise chemical agents in the construction of the product to aid the grinding process. Some of these may be harmful to health if inhaled directly. Consult with the manufacturer or supplier to provide adequate protection information.

Safety instructions provided by the machine manufacturers must be followed at all times. Adequate machine guarding must be provided and used at all times.

Coated abrasives should not be used near flammable material or in an environment where there is a risk of fire or explosion.

Grinding sparks should be directed away from the face and body, away from sensitive surfaces and if possible, be directed into the machine guard or onto the floor.

Dust extraction equipment must be used wherever available. Inhalation of dust particles must be avoided. Suitable dust extraction systems should be provided on all dry grinding operation to ensure that the maximum dust level in the atmosphere does not exceed 10 milligrams per cubic metre. The standard of dust extraction must take into account the volume and toxic nature of the dust.

Check the abrasives product and the work piece before use to ensure suitability. It is recommended that the original supplier be consulted should it be thought necessary to make any modifications of the abrasives used.

Portable grinding equipment must never be released from the hand unless the machine working parts have come to a complete stand still. When changing abrasive products the machines on which they are used should be disconnected from the energy source.

Observe the manufacturers stated "shelf life" which should not be exceeded.

SECTION 3 Belts

3.1 Preparation for Use
Belts should be checked prior to use for tears or holes. This is particularly important in the case of partly used belts, or belts that have been left on a machine for any length of time, e.g. overnight.

On removal from their original packaging, belts should be hung from a drum or rod of minimum diameter 50mm for narrow belts and 300mm for wide belts. They should never be hung from a nail or peg as this may cause cracking and subsequent failure in use.

Wide belts should be preconditioned by hanging in close proximity to the machine for 24 hours prior to use at a recommended temperature of 18-22°C and RH of 45% to 65%.

Care should be taken to ensure that lap jointed belts are run in the correct direction as indicated.

Belts should not be torn or cut down to a narrower size, as this may impair the joint and render it unsafe for use. Neither should they be shortened unless fully trained and properly supervised staff exists for rejoining to the requisite standard for safe operation.

3.2 Recommendations for Use:
While starting, adjusting, or running, the belt should be adequately guarded.

No attempt should be made to remove a belt from a machine that is not stationary.

Belt support devices, e.g. contact wheels, platens, idler pulleys, etc, should be kept in good condition at all times and no attempt should be made to run a belt on a damaged or faulty support device.

It is recommended that "slack of the belt" operations be carried out only on machines designed for the purpose and incorporating adequate guarding arrangements.

To avoid belt breakage, belts, particularly if wide, should not be left under tension on a stationary machine for periods exceeding 30 minutes. In off-hand working, the use of the edge of the belt should be avoided if possible. If unavoidable, extra care should be taken preferably by running the belt in the direction away from the operator.

Jigs, fixture s and clamping devices should be maintained in such a condition that the work piece is securely held during the whole of the working cycle. Machines fitted with magnetic devices (other than permanent magnets) should be equipped with additional guarding in case of power failure.

On machines fitted with "pinch" or "hold-down" rollers, the rollers should be maintained and adjusted so as to ensure proper control over the in and out feeds of the work piece. Components being processed should bridge both rollers.

Abrasive belts should be used dry, unless they are specifically designed for wet grinding and then with a recommended non-water based lubricant,

Belt machines should not be stopped by the application of pressure to the belt surface or motor shaft. They should be allowed to stop in their own time or by application of a brake if fitted.

The following belt speed for grinding or polishing in metres per second are recommended:

Aluminium 23-28 Nickel//Chrome 13-18
Brass/Bronze 25-30 Plastics 15-20
Copper 20-25 Plywood 25-35
Fibreglass 25-35 Rockide 7-10
Glass 13-18 Rubber (Hard) 30-50
Grey Cast Iron 22-25 Carbon Steel 22-25
Mild Steel 22-25 Wood 30-35
Stainless Steel 22-25 Titanium 10-13
SECTION 4 Vulcanised Fibre Discs

4.1 Preparation for Use:
Fibre discs have been designed for use with portable angle grinders and must be used in conjunction with a flexible back-up pad designed for this product use. Do not use other fibre discs as a substitute for back-up pad. The diameter of the disc must be at least 3mm but not more than 15mm greater than the diameter of the back-up pad.

The degree of flexibility of a back up pad can influence the performance of a fibre disc and it is recommended that the manufacturer or supplier of the fibre disc be consulted for advice.

Do not use a fibre disc which is damaged, misshapen or modified in any way. Always check visually for damage before use. Make certain both the disc and the back-up pad are fitted correctly to the machine spindle.

The maximum peripheral operating speed of a fibre disc is 80 m/s. The maximum operating speed in rpm appears on the disc backing. In no circumstances should the speeds be exceeded.

The spindle speed of the machine must never exceed the maxim um operating speed of the disc.

Spindle speeds in rpm corresponding to 80 m/s for different disc diameters are given below:

Disc Diameter 80 m/sec Max rpm
80mm 19,100
100mm 15,300
115mm 13,300
125mm 12,300
150mm 10,200
180mm 8,600
200mm 7,650
235mm 6,500


4.2 Recommendations for Use:

The fibre disc should only be brought into contact with the workpiece when the machine is running at its operational speed.

The fibre disc should be applied to the workpiece at the shallowest angle possible - about 10 degrees is recommended.

Grind "off" an edge rather than "into" it when grinding rough welds or metal edges.

Do not attempt to use a fibre disc for slot grinding, cutting-off or wet grinding. After use the angle grinder should be stored with care. The face of the disc must not be in contact with the floor or work bench.

SECTION 5 Flap Discs

5.1 Preparation for Use:
Flap discs have been designed for use with portable angle grinders and a support pad should be used if specified by the manufacturers.

Damaged, misshapen or modified flap discs should not be used. Always ensure that the flap disc and the support pad are safely and centrally fixed to the machine spindle.

Do not use a flap disc with an oversize or undersize bore. The maximum peripheral operating speed and the maximum rpm of a flap disc should not be exceeded. Refer Section 4.1 - Fibre Discs.

The spindle speed of the machine in RPM must be equal to or less than the maximum operating speed sho wn on the flap disc.

5.2 Recommendation for Use:
The flap disc should only be brought into contact with the workpiece, when the machine is running at is operational speed.

Flap discs are supplied by manufacturers in two shapes. FLAT and CONICAL. For optimum results it is recommended to apply the flap discs to the workpiece at an angle as follows:

Flat type       -       10° to 15°
Conical type       -       15° to 30°

Grind "off" an edge rather than "into" it when grinding rough welds or metal edges.

Do not attempt to use a flap disc for slot grinding, cutting -off or wet grinding. After use the angle grinder should be stored with care. The face of the flap disc must not be in contact with the floor or workbench.

SECTION 6 Paper, Cloth and Combination Discs

6.1 Preparation for Use:
Should the product be required for wet sanding, confirm with the manufacturer or supplier before use that the product is waterproof.

Discs should be used only on machines with a suitable support (back up) pad designed for the purpose and maintained in good condition.

It is recommended that discs be used only on support pads that are clearly marked with the maximum permitted running speed. The speed stated should not be exceeded.

Discs and support pads should not be modified in any way. They should be used only in their original size and shape, as supplied.

Damaged or misshapen abrasive discs or support pads should not be used.

The discs should extend symmetrically to no more than 2mm beyond the outer rim of the support pad.

Care should be taken to ensure that discs without a centre hole are mounted centrally on the support pad.

6.2 Recommendations for Use:
Only start to grind when the machine is up to speed, except on pneumatic random orbital machines, which must be started with light pressure on the disc.

Sanding disc machines should be operated with the disc making the shallowest angle possible with the workpiece.

Never attempt to use the edge of a sanding disc for slot grinding or a cutting operation.

After use the machine should be stored carefully. The face of the abrasive should not be in contact with the floor or work bench.

SECTION 7 VELCRO (Hook & Loop) and PSA Mounted discs

7.1 General Information:
These discs are mounted on the face of rubber, foam rubber or plastic foam type back-up pads. Use is made of either VELCRO (hook & loop) or a pressure sensitive adhesive (PSA) for affixing the abrasive disc to the support (back-up) pad.

The strength(firmness) of the back-up pad determines the maximum operating speeds, which may be employed.

7.2 Preparation for Use:
Ensure the correct machine with the correct operating speed is being used.

With PSA (self-adhesive) discs, care should be taken to ensure the support pad faces are free of dust or other extraneous matter prior to mounting. Damaged or misshapen abrasive discs or support pads should not be used.

7.3 Recommendations for Use:
Care must also be taken to ensure that heat generation when sanding is limited as both VELCRO and PSA discs are affected by heat, which could cause failure of the fixture.

When used in conjunction with self-adhesive discs, portable (hand held) machines should be firmly held when started, with the disc being in light contact with the workpiece. Fixed machines, i.e. not hand held, should be allowed to come up to speed before use.

7.4 Recommended operating speeds:

Fibre disc pad (VELCRO)
Dia Type Firmness Max speed m/s
178mm Rubber Soft/Medium/Hard 80


Mini sanders (VELCRO)
Dia(mm) Thickness (mm) Mandrel dia(mm) Max speed m/s
25 2 3 33
25 15(foam) 3 25
50 2 6 33
50 15(foam) 6 25
75 2 6 33
75 15(foam) 6 25


DIY pad (VELCRO or PSA) - used on portable electric drills
Dia(mm) Thickness (mm) Mandrel dia(mm) Max speed m/s
125 6 or 10 6 27
150 6 or 10 6 27


Foam rubber cushion pads (VELCRO or PSA) - plastic back-up
Dia(mm) Thickness (mm) Attachment Max speed m/s
180 15 5/8" Whit or M14x2 thread 60
200 15 5/8" Whit or M14x2 thread 60


Rotary orbital pads (VELCRO or PSA)
Dia(mm) Thickness (mm) Attachment Max speed m/s
125 10 5/16" Unf24 60
150 10 5/16" Unf24 60
SECTION 8 Flange Mounted Flap Wheels:

8.1 Preparation Before Use:
Flap wheels manufactured with coated abrasives, which require mounting flanges to be fitted, must only be used on machines specifically designed for this purpose.

Always use the associated arbor or mounting flanges supplied by the wheel manufacturer. Ensure that the wheels are mounted strictly in accordance with the manufacturers instructions. Ensure that the wheel is centrally and securely mounted on the machine and that the wheel runs in the direction of the directional arrow marked on blotter or label.

Check that the maximum operating speed on the wheel, given in RPM, is higher than or equal to the spindle speed of the machine. Never exceed the maximum operating speed recommended by the manufacturer.

8.2 Recommendations for Use.
Flap wheels may be used dry or with grinding oil. Reduce contact pressure at lower speeds. Theworking pressure must never cause an excessive flap deflection. When grinding with a flap wheel fitted to a stationary machine ensure the work piece is positioned and fed against the rotation of the flap wheel.

If the wheel has been used with a lubricant, run the machine up to speed progressively.

Only bring the flap wheel into contact with the workpiece when the spindle is "up to speed". When finishing a wet grinding operation turn off the coolant feed and allow the flap wheel to run until no further coolant is ejected.
The maximum operating peripheral speed for flap wheels is 50m/sec. Speed in RPM is as follows;

Wheel
Dia (mm)
Max Speed RPM Wheel
Dia (mm)
Max Speed RPM
100 9500 250 3800
150 6300 300 3100
165 5700 350 2700
200 4700 400 2300


8.3 Recommended Machine Required Power Output:
Dia
mm
Width
mm
Watts
100-165 100-165 Min. 1000
100-165 50 Min. 1500
200-250 25-50 Min. 1500

Note: For dimensions outside of this table consult with the manufacturer.

8.4 Recommended Machine Shaft dimensions:
Flap wheels should not be used on machines with shaft dimensions less than indicated in the following table.

Face Width
Wheel
dia mm
25-30
mm
50
mm
75
mm
100
mm
150
mm
Greater than
150mm face width
100 13 15 20 20 - Consult fitting
with
Manufacturer
150 13 16 20 20 -
165 13 16 20 20 -
200 13 20 25 25 -
250 20 20 25 25 -
300 20 25 32 32 45
350 25 25 51 51 51
400 25 32 51 51 51
SECTION 9 Spindle Mounted Flap wheels

9.1 Preparation For Use:
Ensure that the spindle i s correctly centred in the chuck or collet, and is fixed securely,

Spindle mounted flap wheels must not be run at a speed higher than recommended by the manufacturer and the spindle speed in RPM must never exceed that specified for the wheel.

9.2 Recommendations for Use:
Spindle mounted flap wheels perform best at peripheral speeds of between 15m/sec and 20m/sec, where the optimum balance between stock removal, contour matching behaviour and surface finish is achieved.

To achieve higher stock rem oval rates it is recommended to use a coarser grit rather than more contact pressure, which may cause premature flap wheel.

Do not put the mounted flap wheel in contact with the work material until the wheel is "up to speed".
Grind "off" an edge rather than "into" it when grinding rough welds or edges.

To prevent the spindle becoming loose in the chuck or collet do not use excessive pressure whengrinding.

Wheel
Dia (mm)
Max Speed RPM Wheel
Dia (mm)
Max Speed RPM
20 28700 50 11500
25 22900 60 9600
30 19100 80 7200
40 14300    
SECTION 10 Spirally wound Bands and Sleeves

10.1 Preparation For Use:
Care should be taken to ensure that the band diameter exactly matches that of the support wheel or mandrel.

Support wheels and mandrels should be kept in good condition and free from damage.

Bands and sleeves should not be modified in any way. They should be used only in the original size and shape, as supplied.

The shank of the mandrel which holds the band or sleeve must be gripped by at least 10mm in the machine collet.

Bands and sleeves should not be run at speeds in excess of peripheral speed of 60 m/sec.

10.2 Recommendations for Use:
Do not start grinding until the machine is "up to speed".

When grinding sharp edges and out-lines, grind "off" the edge rather than "into" it.

To prevent the band or sleeve becoming loose on the mandrel do not use excessive pressure when grinding.

As a general "rule of thumb" the recommended peripheral operating speed for bands and sleeves is between 20m/sec and 30 m/sec but users should be guided by the recommendations of the manufacturer.
SECTION 11 Orbital/dual-action sheets

11.1 Preparation For Use:
Sheets should be used only on machines with a suitable support pad designed for the purpose and maintained in good condition at all times.

Sheets should be of the correct size for the machine support pad and should not be used in a misshapen or damaged condition.

With "VELCRO" backed or self-adhesive sheets care should be taken not to exceed the manufacturer’s stated shelf life and to ensure that dust or other extraneous matter prior to mounting do not contaminate the adhesive or support pad face.

Not more than one sheet at a time should be loaded onto the support pad and be secured with retaining clips.

11.2 Recommendations for Use:
Use only a light pressure at first when sanding with "VELCRO" or self-adhesive backed sheets. Do not allow overheating of the sheet to occur.

After use the machine should be stored carefully. The face of the abrasive should not be in contact with the floor or workbench.

SECTION 12 General

Formula Examples:

13.1 To find:
Surface speed per minute of a contact wheel or belt.

Given
RPM of contact wheel and outside diameter (o/d)
Surface speed in metres per second = O/D x p (3.1416) x RPM

i.e. 150mm O/D x 3.1416 x 4000 RPM
1000 x 60


= 31.41 metres/sec

13.2 To Find:
RPM of spindle

Given
Desired surface speed in metres per second and outside diameter of contact wheel:

RPM = M/s x 1000 x 60
p (3.1416) x D


= 31 m/sec x 1000 x 60
3.146 x 150


= 1860,000
471.24


= 3947 RPM

13.3 To Find:
Size of contact wheel

Given
Desired surface speed and RPM:

O/D = Metres/sec x 1000 x 60) ÷ 3.1416
RPM


= (32 metres/sec x 1000 x 60) ÷ 3.1416
4000 RPM


= (1,920,000) ÷ 3.1416
(4000 RPM)


= 480
3,1416


= 152mm