Bsi bs en 12413 2007 + a1 2011

In the revised Table 11 now Table 4 are there only relations between the range of vs, the safety factor Sbr and burst speed factor fbr; d in Clause 5.1.3 "Side load capacity" new Clause

Bonded abrasive products

Products consisting of abrasives e.g aluminium oxide, silicon carbide held together by a bond

Bonded abrasive products within the meaning of this standard are all products as defined, see for example by ISO 525.

Grinding machines

Machines that are fixed in position during operation, see for example EN 13218 Included are fixed swing-frame machines and mobile machines clamped firmly in position during use

Machines that are not fixed in position during operation They are manually guided (but not supported) by hand

3.2.4 Machines with totally enclosed working area

Stationary machines are equipped with protective guards that ensure machining processes, including the loading and unloading of workpieces, are conducted safely within the machine This design effectively safeguards individuals from hazards associated with the potential bursting of abrasive products.

Grinding method

Grinding with the periphery of the wheel with no or limited side loads

Grinding with the face of the wheel

Cutting-off or slotting with the periphery of the cutting-off wheel

Grinding with high contact pressure for steel conditioning.

Type of application

Feed movements of the grinding tool and/or the workpiece are guided by mechanical means

Feed movements of the grinding tool and/or the workpiece are manually guided by the operator

Grinding machine is entirely guided by the operator's hands

Type of grinding machine Type of application Abrasive product Workpiece

Stationary machines Mechanically guided grinding

Guided mechanically Fixed Guided mechanically Guided mechanically

Stationary and mobile machines Manually guided grinding

Hand-held machines Hand-held grinding Guided by hand Fixed

Symbols

Abbrevia- tions Designation Definition Unit n ab Deflection speed of mounted points

Revolutions per minute at which the spindle of mounted points is deflecting under centrifugal force

1/min n max Maximum permissible speed of rotation

The new abrasive product operates at a maximum speed of 1/min, with a corresponding maximum permissible peripheral speed of m/s The safety test speed is defined as the peripheral speed at which the manufacturer tests the abrasive products, measured in m/s Additionally, the test speed factor is denoted as f pr.

Safety test speed divided by maximum operating speed: s pr v pr f = v — f br Burst speed factor

The minimum bursting speed is defined as the peripheral speed that an abrasive product must achieve to avoid breaking due to centrifugal force, measured in meters per second (m/s) In contrast, the maximum operating speed refers to the highest peripheral speed at which the abrasive product can function safely without failure The relationship between these speeds is crucial for ensuring the safe operation of abrasive products.

S br Safety factor against bursting due to centrifugal force

Bursting speed divided by maximum operating speed, all squared:

S ab Safety factor of spindle deflection for mounted points

Deflection speed divided by maximum permissible speed of rotation: n max

A Impact resistance Resistance of a rotating abrasive product to lateral impact Nm

F S1 Single point side load Resistance of a rotating abrasive product to lateral single point load N

F S3 Three point side load Resistance of a rotating abrasive product to lateral three point load N

Table 3 — List of significant hazards

Relevant clauses in this standard

Ejection of parts 1 Wheel breakage caused by

— improper use (mounting and grinding process)

Vibration Hand arm vibration on hand-held machines caused by

General requirements

Abrasive products must be engineered to withstand anticipated forces and loads during intended use, ensuring they are free from visible defects and meet the specified requirements outlined in the subsequent clauses.

Abrasive products shall be manufactured for maximum operating speeds according to the following range:

The only exception to this is where the application requirements dictate an intermediate speed.

Strength requirements

Abrasive products — with the exception of mounted wheels and points — shall have a safety factor against bursting due to centrifugal forces at their maximum operating speed as given in Table 4

Type of machine Type of abrasive product

Mobile machines Grinding and cutting-off wheels ≤ 100 3,5 1,87

> 80 3,5 1,87 a Only manually guided cutting-off

5.2.2 Safety factors for mounted wheels and points

Mounted wheels and points must maintain a safety factor of S br = 3 to prevent bursting from centrifugal forces at their maximum operating speed Additionally, the spindle should have a safety factor against deflection of S ab = 1.3 For more detailed requirements, please refer to Annex B.

Depressed-centre wheels, straight cutting-off wheels and depressed-centre cutting-off wheels for the use on hand- held grinding machines shall have a side load capacity according to Table 5

Table 5 — Side load capacity of abrasive products for the use on hand-held machines

Abrasive product Maximum operating speed Outside diameter

Single point side load test

Three point side load test Impact test

Single point side load Three point side load Impact resistance v s D F S1 F S3 A m/s mm N N Nm

Straight and depressed-centre cutting-off wheels

350/356 125 150 5,4 400/406 125 150 5,4 a According to ISO 525 b With back-up pad as intended for the type of application.

Dimensional requirements

5.3.1 Dimensional limitations and maximum operating speeds

Bonded abrasive products shall comply with the dimensional limitations and maximum operating speeds as specified in Table 6

Table 6 — Dimensional limitations and maximum operating speeds

Maximum operating speeds and dimensional limitations Standard operating speeds Special operating speeds m/s m/s Dimensional limitations

Types of bond b Dimensional limitations

V B BF R RF E MG PL V B BF R RF PL

Mechanically guided grinding totally enclosed

Mechanically guided high pressure grinding

Mechanically guided high pressure grinding totally enclosed

Stationary and mobile grinding machines

**) D > 1 000 mm a Definitions see 3.2 and 3.3 b Types of bond and designation examples see ISO 525

Cemented or clamped cylinder wheel

D × T × W b a Definitions see 3.2 and 3.3 b Types of bond and designation examples see ISO 525

Wheel tapered on one side

Wheel tapered on both sides

D × T× H b a Definitions see 3.2 and 3.3 b Types of bond and designation examples see ISO 525

Wheel recessed on one side

E ≥ 0,50 T 80 80 80 80 80 — Mechanically guided grinding totally enclosed

Stationary and mobile grinding machines

D × T × H-P × F b a Definitions see 3.2 and 3.3 b Types of bond and designation examples, see ISO 525

Wheel recessed on both sides

D × T × H-P × F/G b a Definitions see 3.2 and 3.3 b Types of bond and designation examples see ISO 525

Manually guided grinding (tool sharpening)

Saucer wheel Mechanically guided grinding E ≥ 0,5 T 32 40 — 40 — — — 40 E ≥ 0,5 T 50 50 — 50 — —

Manually guided grinding (tool sharpening)

D/J × T/U × H-K b a Definitions see 3.2 and 3.3 b Types of bond and designation examples, see ISO 525

Wheel relieved on one side

Wheel relieved on both sides Mechanically guided grinding

D/K × T/N × H b a Definitions see 3.2 and 3.3 b Types of bond and designation examples, see ISO 525

Wheel relieved on one side and recessed on the other side

Wheel relieved and recessed on one side Mechanically guided grinding

Wheel relieved and recessed on one side and recessed on the other

Wheel relieved and recessed on one side and relieved on the other side Mechanically guided grinding

D/K × T/N × H-P × F b a Definitions see 3.2 and 3.3 b Types of bond and designation examples, see ISO 52

Wheel relieved and recessed on both sides

Depressed-centre grinding wheel cone shaped

Depressed-centre semi-flexible wheel

D × U × H b a Definitions see 3.2 and 3.3 b Types of bond and designation examples, see ISO 525

Maximum length out of clamping head

Cemented or clamped, disc wheel

Disc wheel with inserted nuts

Cylinder wheel with inserted nuts Mechanically guided grinding

D × T × W b a Definitions see 3.2 and 3.3; b Types of bond and designation examples, see ISO 525;

Double hubbed wheel Mechanically guided grinding

Hand-held cutting-off machines

D × T × H b a Definitions see 3.2 and 3.3 b Types of bond and designation examples, see ISO 525

Depressed centre cutting-off wheel

Hand-held cutting-off machines

D × U × H b a Definitions see 3.2 and 3.3 b Types of bond and designation examples, see ISO 525

Mechanically guided grinding (internal grinding)

D × T × S d b a Definitions see 3.2 and 3.3 b Types of bond and designation examples, see ISO 525 c For maximum permissible speeds according to shape, dimensions and overhang length, see Annex C

5.3.2 Limit deviations and run-out tolerances

All products shall conform to the values specified in ISO 13942 as far as they are listed therein.

Admissible unbalance

All products for the use on hand-held machines shall conform to the values specified in EN ISO 6103 as far as they are listed therein.

Marking

Abrasive products shall be marked according to Annex A.

Blotters

Blotters shall be supplied by the manufacturer, supplier or importer where these are required for a safe mounting and use of the abrasive product

Blotters must be constructed from appropriate compressible materials, with their shape, dimensions, and composition tailored to the specific application and intended use It is essential that when using water-based coolants, the blotter material retains its compressibility and physical functionality without degradation.

Blotters can serve as a label for the marking provided the marking requirements of this standard are met and the blotter is firmly attached to the wheel

6 Verification of the requirements and inspection

Verification methods

6.1.1 Verification of the general requirements

Abrasive products shall be inspected for visual defects Damaged abrasive products shall be destroyed

The ring test shall be performed on vitrified abrasive products with D > 80 mm, with the exception of cemented and nut inserted abrasive products

In the ring test, the abrasive products are tapped with a non-metallic object An undamaged abrasive product will give a clear tone, a damaged abrasive product produces a damp or ratting tone

The safety speed test is essential for identifying faults that significantly impact the strength of bonded abrasive products During this test, the product is securely mounted in a clamping device on a test rig and subjected to increasing revolutions until reaching the designated test speed According to Table 2, the test speed is calculated based on the safety factors listed in Table 4, with a factor of 1.1 for safety factors of 1.75 and 2, and a factor of 1.2 for all other products.

6.1.2 Verification of the strength requirements

6.1.2.1 Verification of the safety factor (Bursting speed test)

The safety factor compliance, specifically the verification of bursting strength, is assessed through a centrifugal force test In this test, the abrasive product is secured in a clamping device on an appropriate test rig and subjected to gradually increasing rotational speeds until reaching the minimum bursting speed The rotation speed is measured with an accuracy of ± 1%, and the bursting speed of the abrasive product is detected and documented using a suitable device.

Bonded abrasive products must meet the minimum bursting speed requirement during testing without breaking It is important to note that all products undergoing this bursting speed test will be destroyed.

6.1.2.2 Verification of side load capacity

6.1.3 Verification of the dimensional requirements

Compliance is checked on the basis of the dimensional data and the data in the drawings using suitable measuring means, e.g limit gauge, calliper gauges, electronic measuring machines

6.1.4 Verification of the admissible unbalance

Verification by using the methods in EN ISO 6103

Verification of the marking data is effected by visual inspection

6.1.6 Verification of the requirements for blotters

Verification is effected by dimensional and visual inspection.

Scope of inspection by the manufacturer

Table 7 outlines the essential inspection requirements during fabrication, assuming that the bursting speed test, along with any necessary side load and impact tests, have been successfully conducted as type tests, and that the production of abrasive products occurs under controlled conditions.

Table 7 — Minimum scope of inspection

Abrasive products Maximum operating speed v s m/s

Test and minimum percentage of manufacturing batch to be tested a

Designation Type Bond Dimensions mm

Straight cutting-off wheels not reinforced 41 B, R, E

Straight and depressed-centre cutting–off wheels, reinforced 41, 42 BF, RF

Straight and depressed-centre grinding wheels reinforced, coolie-hat wheels, flexible wheels

Straight grinding wheels, highly compressed, for high-pressure grinding

Disc wheels and cylinder wheels, bolted, cemented or clamped to a support plate

!All other abrasive products all

Manufacturers must ensure that at least one piece per batch meets the production rate requirements Additionally, they have the option to select either the safety speed test or the bursting speed test when both are deemed acceptable.

Manufacturers, suppliers, or importers of abrasive products must provide users with essential safety information and recommendations for proper application This information should include general details about the products and their properties, guidelines for handling and storage, criteria for selecting the appropriate products, necessary conditions to meet before use, mounting instructions, and procedures for grinding and cutting operations.

 malpractice and incorrect use g) Content and meaning of marking and supplied information h) Restriction to use

The safety recommendations intended as information for use shall be brought to the attention of the user and may be provided

 supplied with the abrasive product

 in the course of training arrangements

 as guidance for practical use

Content of marking

Table A.1 — Marking of abrasive products

Manu- facturer, supplier, importer, trademark

Maximum permissible speed of rotation of the unused abrasive product

Abrasive wheels (straight, tapered, hubbed, recessed, relieved, depressed centre, cutting-off wheels, semi-flexible)

Cup wheels, dish and saucer wheels, disc wheels, cylinder wheels cemented or clamped

Mounted wheels and points X X X — X X — X Small diameter wheels with D ≤80 mm X X X X X X X X

Abrasives products with magnesite bond X X X X X X — X a Option: Additional marking with colour code in accordance with Annex D

Instead of the manufacturer name, supplier or importer their registered trademark may be shown

Abrasive products  nominal dimensions in particular the diameter of the bore (e.g H = 22,23 mm for abrasive products to use on hand-held grinding machines) in accordance with ISO 525

Mounted wheels and points  nominal dimensions, diameter of the spindle and minimum clamping length

Cones and plugs  nominal dimensions, thread diameter and length of insert

Segments, disc wheels, cylindrical wheels cemented, bolted or clamped to a support plate  manufacturer's code e.g drawing number

Specification mark in accordance with ISO 525 Minimum information required: Abrasive type, grain size, grade or hardness, type of bond and use of reinforcement e.g A46KV, A24SBF

Maximum operating speed in metres per second

Maximum permissible speed of rotation in 1/min The speed of rotation marked on the product should be according to Annex E

For mounted wheels and points, the maximum permissible speed of rotation as a function of the relevant overhang and the minimum length of spindle within the collet shall be given

An example for a calculation method for the determination of the permissible speeds of rotation is given in Annex B

For declaration of conformity, the abrasive products shall be marked with:

Abrasive products for which certain grinding procedures, grinding machines and certain applications have to be obeyed shall be marked with the corresponding restrictions of use according to Table A.2

Restrictions of use must be presented in full text or as a pictogram, as outlined in Table A.2 Additionally, a short sign can be used, but it is essential that the complete wording is included on a label attached to the smallest packaging unit.

Abrasive products must feature a traceability code to guarantee identification and traceability, linking each product to a specific production batch This code may include elements such as a production or batch number, expiry date, or series number.

Table A.2 — Restrictions of use (RE)

Short sign Restriction to use Description Pictogram

RE1 Not permitted for hand-held machines

Abrasive product only for use on stationary machines

This restriction only applies to abrasive products not for use on hand-held machines but capable of being mounted on such machines

RE3 Not permitted for wet grinding Abrasive product only suitable for dry grinding

RE4 Only permitted for totally enclosed working area

Abrasive product only for use on stationary machines the guarding of which is accepted as TOTALLY ENCLOSED WORKING AREA

RE6 Not permitted for face grinding

Abrasive product only for use on cutting-off

This restriction only applies to abrasive products for use on hand-held machines

RE8 Only permitted with back-up pad

Abrasive product only for use with additional appropriate back-up pad

NOTE Colour design of the symbols in accordance with ISO 3864-2, wherever possible

Additional inscriptions on the abrasive products such as ISO type number and manufacturer's product name is permitted provided legibility of the data required according to Table A.1 is not impaired

A.1.2.2 Abrasive products for hand-held machines

Abrasive products featuring bond types B and BF, intended for hand-held grinding or cutting-off machines, must display an expiry date This expiry date should not exceed three years from the manufacturing date and is formatted as month and year, for example, 04/2009.

If wheels need to be mounted in a specific position on the spindle they shall be marked in such a way as to clearly indicate in this position

A.1.2.4 Multiple or gang mounted wheels

Wheels that are designed for multiple or gang mounting must be clearly marked to ensure proper installation on the machine spindle, and each wheel should be distinctly identified as part of the specific set.

Abrasive products with magnesite bond shall be marked with a date of expiry

The date of expiry shall at the longest be within 1 year from the date of manufacture It is expressed as month and year e.g 04/2009.

Execution of marking

The marking shall be indelible and legible

Marking should be applied directly on the abrasive product, a fixed blotter, or a label The traceability code must be displayed on the product or its smallest packaging.

For abrasive products exceeding 80 mm in outside diameter, if complete information cannot be provided on the product, blotter, or label, it is essential that the abrasive product is marked with its maximum operating speed, as long as the product's surface and shape allow for such marking.

For products with an outside diameter of D ≤ 80 mm, mounted points and wheels and segments, the specified information can appear on a label fixed to the smallest packaging unit

Example calculation of the maximum permissible speeds of rotation

According to 5.2.2, mounted wheels and points shall have a safety factor against deflection of the spindle of

The deflection speed of the spindle's rotation is significantly influenced by the unsupported overhang at the mounted point To maintain safety standards, the maximum allowable rotational speed must be determined based on the length of the spindle within the collet, as outlined in section A.1.1.

The maximum permissible speed of rotation as a function of the unsupported overhang may be determined by calculation, with the following relations (used symbols, see Table B.2):

The approximate centre of gravity distance L M and the reduced mass M shall be determined as a function of the shape of the mounted point, see Table B.1

Table B.1 — Approximate centre of gravity distance L M and reduced mass M

Mounted points Gravity distance L M and reduced mass M

Cylindrical shape with round end

Mounted points Gravity distance L M and reduced mass M

Cylindrical shape with conical end

Table B.2 — Symbols and further calculation quantities

D Outside diameter of mounted point [mm]

L 3 Clamping length of mounted point [mm]

T Overall thickness of mounted point [mm]

E Modulus of elasticity of the spindle material [N/mm 2 ]

R e Yield point of the spindle material [N/mm 2 ] e Mass eccentricity [mm] ρs Specific density of spindle material [g/cm 3 ] ρk Specific density of the abrasive product [g/cm 3 ]

K m Reducing factor of mass a — m sr Reduced mass of spindle b [g] m k Mass of mounted point without spindle [g] m s Mass of spindle [g]

Spindle length inside abrasive product

S a Diameter of spindle inside the abrasive product (S a = S d) for plain spindle [mm] a K m is calculated with following formulae:

33 b m sr is calculated as follows:

Example for application of the calculation method

Table B.3 — Characteristics for the calculation of maximum permissible speed of rotation

Limit deviation of spindle diameter S d h9

Limit deviation of length of spindle L 2 ± 3 mm

Modulus of elasticity of the spindle material E = 210 000 N/mm 2

Yield point of the spindle material R e = 300 N/mm 2

Specific density of spindle material ρs = 7,85 g/cm 3

Density of the abrasive product ρk = 2,5 g/cm 3

B.2.3 Maximum permissible speeds of rotation

Table B.4 — Mounted points cylindrical shape with S d = 8 mm spindle diameter

D T S d L 2 Maximum permissible speeds of rotation n max for overhang length L 0

Verification methods for side load capacity

General

Compliance with side load capacity requirements as outlined in section 5.2.3 is verified using specific methods In all cases, the abrasive product being tested is securely attached to a rotating spindle using flanges, which are sized according to the dimensions specified in Table C.1.

Table C.1 — Outside diameters of flanges for mounting abrasive products for the determination of the side load capacity

Type of abrasive product Outside diameter

Depressed-centre grinding wheels, straight and depressed-centre cutting-off wheels

Hand-held grinding and cutting-off machines

Single point side load

The rotating abrasive product is subjected to lateral loading through a live pressure roll that is consistently fed towards the axis until it breaks The ball bearing pressure roll features an outer diameter of 70 mm to 80 mm, a width of 25 mm, and a convexity of 25 mm It is positioned against one of the lateral faces of cutting-off wheels and the grinding face of depressed-centre grinding wheels The distance \( R \) between the force application point of the pressure roll and the axis of rotation of the abrasive product is measured in millimeters.

The abrasive product must operate at its designated maximum speed, while a pressure roll is applied at a feeding rate of 3 mm/s until the abrasive product fails The force exerted on the pressure roll in the feed direction, known as the single point side load \( F_{S1} \), is recorded.

Figure C.1 — Single point side load test

Three point side load

The rotating abrasive product is stabilized at the rear by two staggered live back-up rolls, while a live pressure roll is positioned at the front, centrally located between the rear rolls, applying pressure along the axis until rupture occurs.

Figure C.2 — Three point side load test

The test conditions align with the single side load test outlined in Clause C.1, where the force exerted on the pressure roll in the feed direction, known as the three-point side load \( F_{S3} \), is measured.

Impact test

The pendulum testing machine applies lateral impacts to a rotating abrasive product until it ruptures, as illustrated in Figure C.3 This machine features a frame housing a pivotable pendulum equipped with a striker and optional additional mass, with adjustable potential working capacity in 50 increments up to 20 Nm without extra mass or 42 Nm with it The striker, measuring 30 mm in diameter and 115 mm in unsupported length, engages the lateral faces of cutting-off wheels and depressed centre grinding wheels The distance \( R \) from the striker's application point to the abrasive product's axis of rotation is crucial for accurate testing.

The abrasive product is initially operated at the specified maximum speed and loaded with the minimum working capacity values outlined in Table C.1, followed by a visual inspection for any damages If no visible damage is detected, the test is conducted again with increased working capacities on the pendulum testing machine The process identifies both the highest working capacity without visible damage and the capacity of the next higher grade, along with any resulting damages.

Colour codes serve as supplementary indicators for maximum operating speeds, as outlined in Table A.1 When utilized, they must adhere to the specifications in Table D.1 It is important to note that colour codes are applicable only to the specific discrete speed values listed in Table D.1, and intermediate speeds should not feature a colour stripe.

Table D.1 — Colour codes and design of colour codes

Colour code Number and Colour Width of colour stripe Width of gap

1 × yellow 5 mm to 20 mm each at least

2 mm, not greater than width of a colour stripe

The colour code stripes must run straight through the center and across the entire diameter of the abrasive product or label, maintaining an even width Additionally, the design of the label should not hinder the clear visibility of the colour code.

Abrasive products in magnesite bond shall be marked with a white colour code independently from their maximum operating speeds

[1] EN 792-7, Hand-held non-electric power tools — Safety requirements — Part 7: Grinders

[2] EN 792-9, Hand-held non-electric power tools — Safety requirements — Part 9: Die grinders

[3] EN 13218, Machine tools — Safety — Stationary grinding machines

[4] EN 60745-2-3, Hand-held motor-operated electric tools — Safety — Part 2-3: Particular requirements for grinders, polishers and disc-type sanders

[5] EN ISO 19432, Building construction machinery and equipment — Portable, hand-held, internal combustion engine driven cut-off machines — Safety requirements and testing (ISO 19432:2006)

[6] ISO 3864-2, Graphical symbols — Safety colours and safety signs — Part 2: Design principles for product safety labels

Tiêu đề	Safety Requirements For Bonded Abrasive Products
Trường học	British Standards Institution
Chuyên ngành	Safety Requirements for Bonded Abrasive Products
Thể loại	Standard
Năm xuất bản	2011
Thành phố	Brussels

Định dạng
Số trang	54
Dung lượng	1,11 MB