cutting table that feeds the rubber forward to the line of cut and
controls the thickness of the slice.Clamping devices should be
available to secure the rubber.The knife should be lubricated
with a mild soap solution to ease the cutting operation.
7.4Skiving Procedure —This procedure is based on com-
mercial leather slitting machinery,and convenient types are
available for cutting about 50-mm (2-in.)wide strips with
thicknesses up to about 12mm (0.5in.).Adjustments should be
available to vary the thickness of cut,and feed rollers should be
provided to transport the material past the knife.Provision
should be made for continuous sharpening of the cutting edge.
Attachments are available for splitting and cutting sections
from cable sheathing and hose.
7.5Buffıng Techniques —Use the buffing techniques de-
scribed below when it is necessary to remove any unevenness
of surface.Uneveness of surface may result from contact with
fabric components,cutting techniques,or other reasons.
7.5.1Abrasive Wheels —The buffing apparatus should con-
sist of a grinder with motor-driven abrasive wheel.It is
important that the wheel should run true,without vibration,and
that the abrasive surface based on aluminum oxide or silicon
pulleyscarbide is true and sharp.The grinder should be equipped with
a slow-feed mechanism so that very light cuts may be made to
avoid over-heating of the rubber.Suitable means should be
provided for securing the rubber to prevent excessive defor-
mation and for controlled traversing of the rubber pass the
abrasive wheel (Note 2).In operation the depth of cut should
not exceed approximately 0.2mm (0.008in.).The successive
cuts should be progressively thinner to avoid over-heating.Do not carry out buffing beyond the point wh
ere unevenness of thickness has been eliminated.For removal of greater thick-nesses of rubber,use the cutting techniques indicated in 7.3and 7.4.N OTE 2—Wheels of 125to 150-mm (5to 6-in.)diameter operating at a surface speed in the range of 2065m/s (40006700ft/min)of grit size 0.42to 1.00mm (grit No.30)for roughing and of grit size 0.18to 0.42mm (grit No.60)for finishing have been found suitable.7.5.2Abrasive Flexible Bands ,The apparatus shall consist of either a motor-driven drum,on which a spiral helix of the abrasive is secured,or two pulleys,one motor-driven and the other adjustable to tension to centralize the movement of the band.The abrasive bands should be of textile or paper,or a combination of the two,with the abradant based on aluminum oxide or silicon carbide bonded to its surface with a resin unaffected by water.Equipment should be provided for slow feeding of the material to the abrasive band and for securing the material without excessive deformation (Note 3).In opera-tion,cuts removing several tenths of a millimetre of rubber are practicable as the heat build up is much lower than with the method of 7.5.1.The buffing may be either against the drum,against one of the pulleys,or against the taut band between the pulleys.N OTE 3—Grit sizes of 0.42to 1.00mm (grit No.30)for roughing and of 0.05to 0.18mm (grit No.100or 180)for finishing with surface speed of the band in the range 2065m/s (40006700ft/min.)have been found
suitable.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard.Users of this standard are expressly advised that determination of the validity of any such patent rights,and the risk of infringement of such rights,are entirely their own responsibility.
This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised,either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters.Your comments will receive careful consideration at a meeting of the responsible technical committee,which you may attend.If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards,100Barr Harbor Drive,West Conshohocken,PA
19428.

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