[Code of Federal Regulations]
[Title 29, Volume 5]
[Revised as of January 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 29CFR1910.215]
[Page 613-625]
TITLE 29--LABOR
CHAPTER XVII--OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT
OF LABOR
PART 1910_OCCUPATIONAL SAFETY AND HEALTH STANDARDS--Table of Contents
Subpart O_Machinery and Machine Guarding
Sec. 1910.215 Abrasive wheel machinery.
(a) General requirements--(1) Machine guarding. Abrasive wheels
shall be used only on machines provided with safety guards as defined in
the following paragraphs of this section, except:
(i) Wheels used for internal work while within the work being
ground;
(ii) Mounted wheels, used in portable operations, 2 inches and
smaller in diameter; and
(iii) Types 16, 17, 18, 18R, and 19 cones, plugs, and threaded hole
pot balls where the work offers protection.
(2) Guard design. The safety guard shall cover the spindle end, nut,
and flange projections. The safety guard shall be mounted so as to
maintain proper alignment with the wheel, and the strength of the
fastenings shall exceed the strength of the guard, except:
(i) Safety guards on all operations where the work provides a
suitable
[[Page 614]]
measure of protection to the operator, may be so constructed that the
spindle end, nut, and outer flange are exposed; and where the nature of
the work is such as to entirely cover the side of the wheel, the side
covers of the guard may be omitted; and
(ii) The spindle end, nut, and outer flange may be exposed on
machines designed as portable saws.
(3) Flanges. Grinding machines shall be equipped with flanges in
accordance with paragraph (c) of this section.
(4) Work rests. On offhand grinding machines, work rests shall be
used to support the work. They shall be of rigid construction and
designed to be adjustable to compensate for wheel wear. Work rests shall
be kept adjusted closely to the wheel with a maximum opening of one-
eighth inch to prevent the work from being jammed between the wheel and
the rest, which may cause wheel breakage. The work rest shall be
securely clamped after each adjustment. The adjustment shall not be made
with the wheel in motion.
(5) Excluded machinery. Natural sandstone wheels and metal, wooden,
cloth, or paper discs, having a layer of abrasive on the surface are not
covered by this section.
(b) Guarding of abrasive wheel machinery--(1) Cup wheels. Cup wheels
(Types 6 and 11) shall be protected by:
(i) Safety guards as specified in paragraphs (b) (1) through (10) of
this section;
(ii) Band type guards as specified in paragraph (b)(11) of this
section; and
(iii) Special ``Revolving Cup Guards'' which mount behind the wheel
and turn with it. They shall be made of steel or other material with
adequate strength and shall enclose the wheel sides upward from the back
for one-third of the wheel thickness. The mounting features shall
conform with all requirements of this section. It is necessary to
maintain clearance between the wheel side and the guard. This clearance
shall not exceed one-sixteenth inch.
(2) Guard exposure angles. The maximum exposure angles specified in
paragraphs (b) (3) through (8) of this section shall not be exceeded.
Visors or other accessory equipment shall not be included as a part of
the guard when measuring the guard opening, unless such equipment has
strength equal to that of the guard.
(3) Bench and floor stands. The angular exposure of the grinding
wheel periphery and sides for safety guards used on machines known as
bench and floor stands should not exceed 90[deg] or one-fourth of the
periphery. This exposure shall begin at a point not more than 65[deg]
above the horizontal plane of the wheel spindle. (See Figures O-6 and O-
7 and paragraph (b)(9) of this section.)
[GRAPHIC] [TIFF OMITTED] TC27OC91.057
Figure No. O-6 Figure No. O-7
Wherever the nature of the work requires contact with the wheel below
the horizontal plane of the spindle, the exposure shall not exceed
125[deg]. (See Figures O-8 and O-9.)
[GRAPHIC] [TIFF OMITTED] TC27OC91.058
Figure No. O-8 Figure No. O-9
(4) Cylindrical grinders. The maximum angular exposure of the
grinding wheel periphery and sides for safety guards used on cylindrical
grinding machines shall not exceed 180[deg]. This exposure shall begin
at a point not more than 65[deg] above the horizontal plane of the wheel
spindle. (See Figures O-10 and O-11 and subparagraph (9) of this
paragraph.)
[[Page 615]]
[GRAPHIC] [TIFF OMITTED] TC27OC91.059
Figure No. O-10 Figure No. O-11
(5) Surface grinders and cutting-off machines. The maximum angular
exposure of the grinding wheel periphery and sides for safety guards
used on cutting-off machines and on surface grinding machines which
employ the wheel periphery shall not exceed 150[deg]. This exposure
shall begin at a point not less than 15[deg] below the horizontal plane
of the wheel spindle. (See Figures O-12 and O-13)
[GRAPHIC] [TIFF OMITTED] TC27OC91.060
Figure No. O-12 Figure No. O-13
(6) Swing frame grinders. The maximum angular exposure of the
grinding wheel periphery and sides for safety guards used on machines
known as swing frame grinding machines shall not exceed 180[deg], and
the top half of the wheel shall be enclosed at all times. (See Figures
O-14 and O-15.)
[GRAPHIC] [TIFF OMITTED] TC27OC91.061
Figure No. O-14 Figure No. O-15
(7) Automatic snagging machines. The maximum angular exposure of the
grinding wheel periphery and sides for safety guards used on grinders
known as automatic snagging machines shall not exceed 180[deg] and the
top half of the wheel shall be enclosed at all times. (See Figures O-14
and O-15.)
(8) Top grinding. Where the work is applied to the wheel above the
horizontal centerline, the exposure of the grinding wheel periphery
shall be as small as possible and shall not exceed 60[deg]. (See Figures
O-16 and O-17.)
[GRAPHIC] [TIFF OMITTED] TC27OC91.062
Figure No. O-16 Figure No. O-17
(9) Exposure adjustment. Safety guards of the types described in
subparagraphs (3) and (4) of this paragraph, where the operator stands
in front of the opening, shall be constructed so that the peripheral
protecting member can be adjusted to the constantly decreasing diameter
of the wheel. The maximum angular exposure above the horizontal plane of
the wheel spindle as specified in paragraphs (b) (3) and (4) of this
section shall never be exceeded, and the distance between the wheel
periphery and the adjustable tongue or the end of the peripheral member
at the top shall never exceed one-fourth inch. (See Figures O-18, O-19,
O-20, O-21, O-22, and O-23.)
(10) Material requirements and minimum dimensions. (i) See Figures
O-36 and O-37 and Table O-9 for minimum basic thickness of peripheral
and side members for various types of safety guards and classes of
service.
(ii) If operating speed does not exceed 8,000 surface feet per
minute cast iron safety guards, malleable iron guards or other guards as
described in paragraph (b)(10)(iii) of this section shall be used.
(iii) Cast steel, or structural steel, safety guards as specified in
Figures O-36 and O-37 and Table O-9 shall be used where operating speeds
of wheels are faster than 8,000 surface feet per minute up to a maximum
of 16,000 surface feet per minute.
(iv) For cutting-off wheels 16 inches diameter and smaller and where
speed does not exceed 16,000 surface feet per minute, cast iron or
malleable iron safety guards as specified in Figures O-
[[Page 616]]
36 and O-37, and in Table O-9 shall be used.
[GRAPHIC] [TIFF OMITTED] TC27OC91.063
Figure No. O-18 Figure No. O-19
correct
Showing adjustable tongue giving required angular protection for all
sizes of wheel used.
[GRAPHIC] [TIFF OMITTED] TC27OC91.064
Figure No. O-20 Figure No. O-21
correct
Showing movable guard with opening small enough to give required
protection for smallest size wheel used.
[GRAPHIC] [TIFF OMITTED] TC27OC91.065
Figure No. O-22 Figure No. O-23
incorrect
Showing movable guard with size of opening correct for full size wheel
but too large for smaller wheels.
(v) For cutting-off wheels larger than 16 inches diameter and where
speed does not exceed 14,200 surface feet per minute, safety guards as
specified in Figures O-27 and O-28, and in Table O-1 shall be used.
(vi) For thread grinding wheels not exceeding 1 inch in thickness
cast iron or malleable iron safety guards as specified in Figures O-36
and O-37, and in Table O-9 shall be used.
(11) Band type guards--general specifications. Band type guards
shall conform to the following general specifications:
(i) The bands shall be of steel plate or other material of equal or
greater strength. They shall be continuous, the ends being either
riveted, bolted, or welded together in such a manner as to leave the
inside free from projections.
(ii) The inside diameter of the band shall not be more than 1 inch
larger than the outside diameter of the wheel, and shall be mounted as
nearly concentric with the wheel as practicable.
(iii) The band shall be of sufficient width and its position kept so
adjusted that at no time will the wheel protrude beyond the edge of the
band a distance greater than that indicated in Figure O-29 and in Table
O-2 or the wall thickness (W), whichever is smaller.
(12) Guard design specifications. Abrasive wheel machinery guards
shall meet the design specifications of the American National Standard
Safety Code for the Use, Care, and Protection of Abrasive Wheels, ANSI
B7.1-1970, which is incorporated by reference as specified in Sec.
1910.6. This requirement shall not apply to natural sandstone wheels or
metal, wooden, cloth, or paper discs, having a layer of abrasive on the
surface.
(c) Flanges--(1) General requirements. All abrasive wheels shall be
mounted between flanges which shall not be less than one-third the
diameter of the wheel.
(i) Exceptions:
(a) Mounted wheels.
(b) Portable wheels with threaded inserts or projecting studs.
(c) Abrasive discs (inserted nut, inserted washer and projecting
stud type).
(d) Plate mounted wheels.
(e) Cylinders, cup, or segmental wheels that are mounted in chucks.
(f) Types 27 and 28 wheels.
(g) Certain internal wheels.
(h) Modified types 6 and 11 wheels (terrazzo).
(i) Cutting-off wheels, Types 1 and 27A (see paragraphs (c)(1) (ii)
and (iii) of this section).
[[Page 617]]
(ii) Type 1 cutting-off wheels are to be mounted between properly
relieved flanges which have matching bearing surfaces. Such flanges
shall be at least one-fourth the wheel diameter.
(iii) Type 27A cutting-off wheels are designed to be mounted by
means of flat, not relieved, flanges having matching bearing surfaces
and which may be less than one-third but shall not be less than one-
fourth the wheel diameter. (See Figure O-24 for one such type of
mounting.)
(iv) There are three general types of flanges:
(a) Straight relieved flanges (see Figure O-32);
(b) Straight unrelieved flanges (see Figure O-30);
(c) Adaptor flanges (see Figures O-33 and O-34);
(v) Regardless of flange type used, the wheel shall always be
guarded. Blotters shall be used in accordance with paragraph (c)(6) of
this section.
[GRAPHIC] [TIFF OMITTED] TC27OC91.066
Figure No. O-24
The Type 27 A Wheel is mounted between flat non-relieved flanges of
equal bearing surfaces.
(2) [Reserved]
(3) Finish and balance. Flanges shall be dimensionally accurate and
in good balance. There shall be no rough surfaces or sharp edges.
(4) Uniformity of diameter. (i) Both flanges, of any type, between
which a wheel is mounted, shall be of the same diameter and have equal
bearing surface. Exceptions are set forth in the remaining subdivisions
of this subparagraph.
(ii) Type 27 and Type 28 wheels, because of their shape and usage,
require specially designed adaptors. The back flange shall extend beyond
the central hub or raised portion and contact the wheel to counteract
the side pressure on the wheel in use. The adaptor nut which is less
than the minimum one-third diameter of wheel fits in the depressed side
of wheel to prevent interference in side grinding and serves to drive
the wheel by its clamping force against the depressed portion of the
back flange. The variance in flange diameters, the adaptor nut being
less than one-third wheel diameter, and the use of side pressure in
wheel operation limits the use to reinforced organic bonded wheels.
Mounts which are affixed to the wheel by the manufacturer shall not be
reused. Type 27 and Type 28 wheels shall be used only with a safety
guard located between wheel and operator during use. (See Figure O-24-
A.)
[GRAPHIC] [TIFF OMITTED] TC27OC91.067
Figure No. O-24-A
Types 27 and 28 wheels, because of their shape, require specially
designed adaptors.
(iii) Modified Types 6 and 11 wheels (terrazzo) with tapered K
dimension.
(5) Recess and undercut. (i) Straight relieved flanges made
according to Table O-6 and Figure O-32 shall be recessed at least one-
sixteenth inch on the side next to the wheel for a distance as specified
in Table O-6.
(ii) Straight flanges of the adaptor or sleeve type (Table O-7 and
Figures O-33 and O-34) shall be undercut so that there will be no
bearing on the sides of
[[Page 618]]
the wheel within one-eighth inch of the arbor hole.
(6) Blotters. (i) Blotters (compressible washers) shall always be
used between flanges and abrasive wheel surfaces to insure uniform
distribution of flange pressure. (See paragraph (d)(5) of this section.)
(ii) Exception:
(a) Mounted wheels.
(b) Abrasive discs (inserted nut, inserted washer, and projecting
stud type).
(c) Plate mounted wheels.
(d) Cylinders, cups, or segmental wheels that are mounted in chucks.
(e) Types 27 and 28 wheels.
(f) Certain Type 1 and Type 27A cutting-off wheels.
(g) Certain internal wheels.
(h) Type 4 tapered wheels.
(i) Diamond wheels, except certain vitrified diamond wheels.
(j) Modified Types 6 and 11 wheel (terrazzo)--blotters applied flat
side of wheel only.
(7) Driving flange. The driving flange shall be securely fastened to
the spindle and the bearing surface shall run true. When more than one
wheel is mounted between a single set of flanges, wheels may be cemented
together or separated by specially designed spacers. Spacers shall be
equal in diameter to the mounting flanges and have equal bearing
surfaces. (See paragraph (d)(6) of this section.)
(8) Dimensions. (i) Tables O-4 and O-6 and Figures O-30 and O-32
show minimum dimensions for straight relieved and unrelieved flanges for
use with wheels with small holes that fit directly on the machine
spindle. Dimensions of such flanges shall never be less than indicated.
(ii) Table O-5, and Table O-7 and Figures O-31, O-33, O-34 show
minimum dimensions for straight adaptor flanges for use with wheels
having holes larger than the spindle. Dimensions of such adaptor flanges
shall never be less than indicated.
(iii) Table O-8 and Figure O-35 show minimum dimensions for straight
flanges that are an integral part of wheel sleeves which are frequently
used on precision grinding machines. Dimensions of such flanges shall
never be less than indicated.
(9) Repairs and maintenance. All flanges shall be maintained in good
condition. When the bearing surfaces become worn, warped, sprung, or
damaged they should be trued or refaced. When refacing or truing, care
shall be exercised to make sure that proper relief and rigidity is
maintained as specified in paragraphs (c) (2) and (5) of this section
and they shall be replaced when they do not conform to these
subparagraphs and Table O-4, Figure O-30, Table O-5, Figure O-31, Table
O-6, Figure O-32, and Table O-8, Figure O-35. Failure to observe these
rules might cause excessive flange pressure around the hole of the
wheel. This is especially true of wheel-sleeve or adaptor flanges.
(d) Mounting--(1) Inspection. Immediately before mounting, all
wheels shall be closely inspected and sounded by the user (ring test) to
make sure they have not been damaged in transit, storage, or otherwise.
The spindle speed of the machine shall be checked before mounting of the
wheel to be certain that it does not exceed the maximum operating speed
marked on the wheel. Wheels should be tapped gently with a light
nonmetallic implement, such as the handle of a screwdriver for light
wheels, or a wooden mallet for heavier wheels. If they sound cracked
(dead), they shall not be used. This is known as the ``Ring Test''.
(i) Wheels must be dry and free from sawdust when applying the ring
test, otherwise the sound will be deadened. It should also be noted that
organic bonded wheels do not emit the same clear metallic ring as do
vitrified and silicate wheels.
[GRAPHIC] [TIFF OMITTED] TC27OC91.068
Figure No. O-25 Figure No. O-26
[[Page 619]]
(ii) ``Tap'' wheels about 45[deg] each side of the vertical
centerline and about 1 or 2 inches from the periphery as indicated by
the spots in Figure O-25 and Figure O-26. Then rotate the wheel 45[deg]
and repeat the test. A sound and undamaged wheel will give a clear
metallic tone. If cracked, there will be a dead sound and not a clear
``ring.''
(2) Arbor size. Grinding wheels shall fit freely on the spindle and
remain free under all grinding conditions. A controlled clearance
between the wheel hole and the machine spindle (or wheel sleeves or
adaptors) is essential to avoid excessive pressure from mounting and
spindle expansion. To accomplish this, the machine spindle shall be made
to nominal (standard) size plus zero minus .002 inch, and the wheel hole
shall be made suitably oversize to assure safety clearance under the
conditions of operating heat and pressure.
(3) Surface condition. All contact surfaces of wheels, blotters and
flanges shall be flat and free of foreign matter.
(4) Bushing. When a bushing is used in the wheel hole it shall not
exceed the width of the wheel and shall not contact the flanges.
(5) Blotters. When blotters or flange facings of compressible
material are required, they shall cover entire contact area of wheel
flanges. Blotters need not be used with the following types of wheels:
(i) Mounted wheels.
(ii) Abrasive discs (inserted nut, inserted washer, and projecting-
stud type).
(iii) Plate mounted wheels.
(iv) Cylinders, cups, or segmental wheels that are mounted in
chucks.
(v) Types 27 and 28 wheels.
(vi) Certain Type 1 and Type 27A cutting-off wheels.
(vii) Certain internal wheels.
(viii) Type 4 tapered wheels.
(ix) Diamond wheels, except certain vitrified diamond wheels.
(6) Multiple wheel mounting. When more than one wheel is mounted
between a single set of flanges, wheels may be cemented together or
separated by specially designed spacers. Spacers shall be equal in
diameter to the mounting flanges and have equal bearing surfaces. When
mounting wheels which have not been cemented together, or ones which do
not utilize separating spacers, care must be exercised to use wheels
specially manufactured for that purpose.
[GRAPHIC] [TIFF OMITTED] TC27OC91.069
[[Page 620]]
Table O-1--Minimum Basic Thickness for Peripheral and Side Members for Safety Guards Used With Cutting-Off Wheels
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cutting off wheel diameters
---------------------------------------------------------------------
Material used in construction of Maximum thickness of 6 to 11 Over 11 to Over 20 to Over 30 to Over 48 to
guard cutting off wheel Speed not to exceed inches 20 inches 30 inches 48 inches 72 inches
---------------------------------------------------------------------
A B A B A B A B A B
--------------------------------------------------------------------------------------------------------------------------------------------------------
Structural steel (min. tensile \1/2\ inch or less.... 14,200 SFPM.......... \1/ \1/ \3/ \3/ \1/8\ \1/8\ \3/ \3/ \1/4\ \1/4\
strength 60,000 p.s.i.). 16\ 16\ 32\ 32\ 16\ 16\
\1/2\ inch or less.... 16,000 SFPM.......... \3/ \1/8\ \1/8\ \1/8\ \3/ \1/8\ \1/4\ \3/ \5/ \1/4\
32\ 16\ 16\ 16\
--------------------------------------------------------------------------------------------------------------------------------------------------------
[GRAPHIC] [TIFF OMITTED] TC27OC91.070
Table O-3--Guide for Construction of Band Type Guards
[Maximum Wheel Speed 7,000 SFPM]
----------------------------------------------------------------------------------------------------------------
Maximum
Minimum Minimum distance
Minimum material specifications Diameter of wheel thickness diameter between
of band A of rivets centers of
rivets
----------------------------------------------------------------------------------------------------------------
Inches
----------------------------------------------------------------------------------------------------------------
Hot rolled steel SAE 1008................ Under 8.......................... \1/16\ \3/16\ \3/4\
8 to 24.......................... \1/8\ \1/4\ 1
Over 24 to 30.................... \1/4\ \3/8\ 1\1/4\
----------------------------------------------------------------------------------------------------------------
[GRAPHIC] [TIFF OMITTED] TC27OC91.071
[[Page 621]]
Table O-5--Minimum Dimensions for Straight Adaptor Flange--for Organic Bonded Wheels Over 1\1/4\ Inches Thick
\1\
[In inches]
----------------------------------------------------------------------------------------------------------------
E--Minimum
B--Minimum D--Minimun thickness F \1\--(D-
Wheel diameter Wheel hole flange thickness of flange E) minimum
diameter diameter of flange at edge of thickness
at bore undercut
----------------------------------------------------------------------------------------------------------------
12 to 14............................................ 4 6 \7/8\ \3/8\ \1/2\
5 7 \7/8\ \3/8\ \1/2\
6 8 \7/8\ \3/8\ \1/2\
Larger than 14 to 18................................ 4 6 \7/8\ \3/8\ \1/2\
5 7 \7/8\ \3/8\ \1/2\
6 8 \7/8\ \3/8\ \1/2\
7 9 \7/8\ \3/8\ \1/2\
8 10 \7/8\ \3/8\ \1/2\
Larger than 18 to 24................................ 6 8 1 \1/2\ \1/2\
7 9 1 \1/2\ \1/2\
8 10 1 \1/2\ \1/2\
10 12 1 \1/2\ \1/2\
12 14 1 \1/2\ \1/2\
Larger than 24 to 30................................ 12 15 1 \1/2\ \1/2\
Larger than 30 to 36................................ 12 15 1\3/8\ \7/8\ \1/2\
----------------------------------------------------------------------------------------------------------------
\1\ For wheels under 1\1/4\ inches thick F dimension shall not exceed 40 percent of wheel thickness.
[GRAPHIC] [TIFF OMITTED] TC27OC91.072
Table O-6--Minimum Dimensions for Straight Relieved Flanges \1\
[In inches]
----------------------------------------------------------------------------------------------------------------
C--Radial width of E--Minimum
B--Minimum bearing surface D--Minimum thickness
A--Diameter of wheel outside ------------------------ thickness of flange
diameter of flange at edge of
of flanges Minimum Maximum at bore recess
----------------------------------------------------------------------------------------------------------------
1................................................... \3/8\ \1/16\ \1/8\ \1/16\ \1/16\
2................................................... \3/4\ \1/8\ \3/16\ \1/8\ \3/32\
3................................................... 1 \1/8\ \3/16\ \3/16\ \3/32\
4................................................... 1\3/8\ \1/8\ \3/16\ \3/16\ \1/8\
5................................................... 1\3/4\ \3/16\ \1/4\ \1/4\ \1/8\
6................................................... 2 \1/4\ \1/2\ \3/8\ \3/16\
7................................................... 2\1/2\ \1/4\ \1/2\ \3/8\ \3/16\
8................................................... 3 \1/4\ \1/2\ \3/8\ \3/16\
10.................................................. 3\1/2\ \5/16\ \5/8\ \3/8\ \1/4\
12.................................................. 4 \5/16\ \5/8\ \1/2\ \5/16\
14.................................................. 4\1/2\ \3/8\ \3/4\ \1/2\ \5/16\
16.................................................. 5\1/2\ \1/2\ 1 \1/2\ \5/16\
18.................................................. 6 \1/2\ 1 \5/8\ \3/8\
20.................................................. 7 \5/8\ 1\1/4\ \5/8\ \3/8\
22.................................................. 7\1/2\ \5/8\ 1\1/4\ \5/8\ \7/16\
24.................................................. 8 \3/4\ 1\1/4\ \5/8\ \7/16\
26.................................................. 8\1/2\ \3/4\ 1\1/4\ \5/8\ \1/2\
28.................................................. 10 \7/8\ 1\1/2\ \3/4\ \1/2\
30.................................................. 10 \7/8\ 1\1/2\ \3/4\ \5/8\
36.................................................. 12 1 2 \7/8\ \3/4\
42.................................................. 14 1 2 \7/8\ \3/4\
48.................................................. 16 1\1/4\ 2 1\1/8\ 1
60.................................................. 20 1\1/4\ 2 1\1/4\ 1\1/8\
72.................................................. 24 1\1/2\ 2\1/2\ 1\3/8\ 1\1/4\
----------------------------------------------------------------------------------------------------------------
\1\ Flanges for wheels under 2 inches diameter may be unrelieved and shall be maintained flat and true.
[[Page 622]]
[GRAPHIC] [TIFF OMITTED] TC27OC91.073
Table O-7--Minimum Dimensions for Straight Flanges--for Mechanical
Grinders 12,500 S.F.P.M. to 16,5 S.F.P.M.\1\
------------------------------------------------------------------------
E--Minimum
B--Minimum D--Minimum thickness F \2\--(D-
Wheel Wheel hole flange thickness of flange E) minimum
diameter diameter diameter of flange at edge of thickness
at bore undercut
------------------------------------------------------------------------
20 6 8 1 \1/2\ \1/2\
20 8 10 1\1/2\ \3/4\ \3/4\
24 12 15 2 1 1
30 12 15 2 1 1
36 12 15 2 1
------------------------------------------------------------------------
\1\ Flanges shall be of steel, quality SAE 1040 or equivalent, annealed
plate, heat treated to R. 25-30.
\2\ For wheels under 1\1/4\ inch thick F dimension shall not exceed 40
percent of wheel thickness.
[GRAPHIC] [TIFF OMITTED] TC27OC91.074
Table O-8--Minimum Dimensions for Straight Flanges Used as Wheel Sleeves for Precision Grinding Only
[In inches]
----------------------------------------------------------------------------------------------------------------
E--Minimum
B--Minimum D--Minimum thickness
Wheel diameter Wheel hole outside thickness of flange
diameter diameter of flange at edge of
of flange at bore undercut
----------------------------------------------------------------------------------------------------------------
12 to 14........................................................ 5 7 \1/2\ \7/16\
Larger than 14 to 20............................................ 5 7 \5/8\ \7/16\
6 8 \5/8\ \7/16\
8 10 \5/8\ \7/16\
10 11\1/2\ \5/8\ \7/16\
12 13\1/2\ \5/8\ \7/16\
Larger than 20 to 30............................................ 8 10 \3/4\ \1/2\
10 11\1/2\ \3/4\ \1/2\
12 13\1/2\ \3/4\ \1/2\
16 17\1/2\ \3/4\ \1/2\
Larger than 30 to 42............................................ 12 13\1/2\ \3/4\ \1/2\
16 17\1/2\ \3/4\ \1/2\
18 19\1/2\ \3/4\ \1/2\
20 21\1/2\ \3/4\ \1/2\
Larger than 42 to 60............................................ 16 20 1 \3/4\
20 24 1 \3/4\
24 29 1\1/8\ \7/8\
----------------------------------------------------------------------------------------------------------------
Note: These flanges may be clamped together by means of a central nut, or by a series of bolts or some other
equivalent means of fastening. For hole sizes smaller than shown in this table, use table 12.
[[Page 623]]
[GRAPHIC] [TIFF OMITTED] TC27OC91.075
[[Page 624]]
Table O-9--Minimum Basic Thicknesses of Peripheral and Side Members for Safety Guards
[In inches]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Grinding wheel diameters
Maximum ---------------------------------------------------------------------------------------------------------------
Material used in construction thickness 3 to 6 inches Over 6 to 12 Over 12 to 16 Over 16 to 20 Over 20 to 24 Over 24 to 30 Over 30 to 48
of guard of ---------------- inches inches inches inches inches inches
grinding -----------------------------------------------------------------------------------------------
wheel A B A B A B A B A B A B A B
--------------------------------------------------------------------------------------------------------------------------------------------------------
Material 2 \1/4\ \1/4\ \3/8\ \5/16\ \1/2\ \3/8\ \5/8\ \1/2\ \7/8\ \5/8\ 1 \3/4\ 1\1/4\ 1
satis- 4 \5/16\ \5/16\ \3/8\ \5/16\ \1/2\ \3/8\ \3/4\ \5/8\ 1 \5/8\ 1\1/8\ \3/4\ 1\3/8\ 1
factory \1\ 6 \3/8\ \5/16\ \1/2\ \7/16\ \5/8\ \1/2\ 1 \5/8\ 1\1/8\ \3/4\ 1\1/4\ \7/8\ 1\1/2\ 1\1/8\
for 8 ...... ...... \5/8\ \9/16\ \7/8\ \3/4\ 1 \3/4\ 1\1/8\ \3/4\ 1\1/4\ \7/8\ 1\1/2\ 1\1/8\
speeds 10 ...... ...... \3/4\ \11/ \7/8\ \3/4\ 1 \3/4\ 1\1/8\ \3/4\ 1\1/4\ \7/8\ 1\1/2\ 1\1/8\
16\
up to 16 ...... ...... ...... ...... 1\1/8\ 1 1\1/4\ 1 1\5/ 1 1\7/ 1\1/ 1\3/4\ 1\3/8\
16\ 16\ 16\
8,000 20 ...... ...... ...... ...... ...... ...... 1\3/8\ 1\1/8\ 1\3/8\ 1\1/8\ 1\1/2\ 1\3/8\ 2 1\5/8\
SFPM.
Cast iron (min. tensile
strength 20,000 p.s.i.)
Class 20.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Material 2 \1/4\ \1/4\ \3/8\ \5/16\ \1/2\ \3/8\ \5/8\ \1/2\ \3/4\ \5/8\ \7/8\ \3/4\ 1 \7/8\
satis- 4 \5/16\ \5/16\ \3/8\ \5/16\ \1/2\ \3/8\ \5/8\ \1/2\ \3/4\ \5/8\ \7/8\ \3/4\ 1\1/8\ \7/8\
factory \1\ 6 \3/8\ \5/16\ \1/2\ \7/16\ \5/8\ \1/2\ \3/4\ \5/8\ \7/8\ \5/8\ 1 \3/4\ 1\1/4\ \7/8\
for 8 ...... ...... \1/2\ \7/16\ \5/8\ \1/2\ \3/4\ \5/8\ \7/8\ \5/8\ 1 \3/4\ 1\1/4\ \7/8\
speeds 10 ...... ...... \1/2\ \7/16\ \5/8\ \1/2\ \3/4\ \5/8\ \7/8\ \5/8\ 1 \3/4\ 1\1/4\ \7/8\
up to 16 ...... ...... ...... ...... \13/ \11/ \13/ \11/ 1 \3/4\ 1\1/8\ \7/8\ 1\3/8\ 1
16\ 16\ 16\ 16\
9,000 20 ...... ...... ...... ...... ...... ...... \7/8\ \3/4\ 1 \3/4\ 1\1/8\ \7/8\ 1\1/2\ 1\1/8\
SFPM.
Malleable iron (min. tensile
strength 50,000 p.s.i.)
Grade 32510.
Materials 2 \1/4\ \1/4\ \5/16\ \5/16\ \3/8\ \3/8\ \1/2\ \7/16\ \5/8\ \1/2\ \3/4\ \5/8\ \7/8\ \3/4\
satis- 4 \1/4\ \1/4\ \1/2\ \1/2\ \1/2\ \1/2\ \9/16\ \1/2\ \5/8\ \1/2\ \3/4\ \5/8\ 1 \3/4\
factory \1\ 6 \3/8\ \1/4\ \3/4\ \5/8\ \3/4\ \5/8\ \3/4\ \5/8\ \13/ \11/ \13/ \11/ 1\1/8\ \3/4\
16\ 16\ 16\ 16\
for 8 ...... ...... \7/8\ \3/4\ \7/8\ \3/4\ \7/8\ \3/4\ \7/8\ \3/4\ \15/ \13/ 1\3/8\ 1
16\ 16\
speeds 10 ...... ...... 1 \7/8\ 1 \7/8\ 1 \7/8\ 1\1/8\ \15/ 1\1/8\ 1 1\7/ 1\1/
16\ 16\ 16\
up to 16 ...... ...... ...... ...... 1\1/4\ 1\1/8\ 1\1/4\ 1\1/8\ 1\1/4\ 1\1/8\ 1\1/4\ 1\1/8\ 1\13/ 1\7/
16\ 16\
16,000 20 ...... ...... ...... ...... ...... ...... 1\3/8\ 1\1/4\ 1\3/8\ 1\1/4\ 1\7/ 1\5/ 2\1/ 1\11/
16\ 16\ 16\ 16\
SFPM.
Steel castings (min. tensile
strength 60,000 p.s.i.)
Grade V60-30.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Structural 2 \1/8\ \1/16\ \5/16\ \1/4\ \5/16\ \1/4\ \5/16\ \1/4\ \5/16\ \1/4\ \3/8\ \5/16\ \1/2\ \3/8\
steel 4 \1/8\ \1/16\ \3/8\ \5/16\ \3/8\ \5/16\ \3/8\ \5/16\ \3/8\ \5/16\ \3/8\ \5/16\ \1/2\ \3/8\
(min. 6 \3/16\ \1/16\ \1/2\ \3/8\ \7/16\ \3/8\ \7/16\ \3/8\ \7/16\ \3/8\ \7/16\ \3/8\ \3/4\ \1/2\
tensile 8 ...... ...... \1/2\ \3/8\ \9/16\ \7/16\ \9/16\ \7/16\ 9
strength 10 \9/16\ \7/16\ \5/8\ \1/2\ \5/8\ \1/2\ \5/8\ \1/2\ \5/8\ \1/2\ \7/8\ \5/8\
60,000 16 ...... ...... ...... ...... \5/8\ \9/16\ \3/4\ \5/8\ \3/4\ \5/8\ \13/ \11/ 1\1/ \13/
16\ 16\ 16\ 16\
p.s.i.) 20 ...... ...... ...... ...... ...... ...... \13/ \11/ \13/ \11/ \7/8\ \3/4\ 1\3/ \15/
16\ 16\ 16\ 16\ 16\ 16\
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The recommendations listed in the above table are guides for the conditions stated. Other material, designs or dimensions affording equal or
superior protection are also acceptable.
[[Page 625]]
Table O-2--Exposure Versus Wheel Thickness
[In inches]
------------------------------------------------------------------------
Maximum
exposure
Overall thickness of wheel (T) of wheel
(C)
------------------------------------------------------------------------
\1/2\....................................................... \1/4\
1........................................................... \1/2\
2........................................................... \3/4\
3........................................................... 1
4........................................................... 1\1/2\
5 and over.................................................. 2
------------------------------------------------------------------------
Table O-4--Minimum Dimensions for Straight Unrelieved Flanges for Wheels
with Threaded Inserts or Projecting Studs
------------------------------------------------------------------------
B \1\--Minimum outside T--Minimum thickness
A--Diameter of wheel diameter of flange of flange
------------------------------------------------------------------------
1 \5/8\ \1/8\
2 1 \1/8\
3 1 \3/16\
4 1 \3/8\ \3/16\
5 1\3/4\ \1/4\
6 2 \3/8\
------------------------------------------------------------------------
\1\ Note: Must be large enough to extend beyond the bushing. Where prong
anchor or cupback bushing are used, this footnote does not apply.
[39 FR 23502, June 27, 1974, as amended at 43 FR 49750, Oct. 24, 1978;
49 FR 5323, Feb. 10, 1984; 61 FR 9240, Mar. 7, 1996]