CHUCK HOLDING POWER INFORMATION

MAGNETIC CHUCKS   & SINE PLATES Holding power varies greatly, depending on the size and thickness of the workpiece, the contact area between the part and the chuck, the material the workpiece is made out of, workpiece surface finish and air gaps between the part and the chuck. Things that create air gaps are air, protective coatings, paint, galvanizing, oil, rust, dirt, etc.  Holding power falls off at the ends and sides of the chuck (where the frame is and therefore no magnets).  Under near ideal conditions at the center of the chuck, using a ground 1" X 1" X 1" cube of CRS, the following average MAXIMUM holding powers were found.

MAGNETIC CHUCK or SINE PLATE TYPE	AVERAGE MAXIMUM HOLDING POWER
8866, A-xx-MS, B-xx-MS, DMB	90-100 PSI
9195, MAI	35-50 PSI
EMC, EMCB, ESP, ESPC	45-55 PSI
MC, MCB, MSP, MSPC	40-55 PSI
MTC	12-18 PSI
RMC	30-35 PSI

The holding powers above should be derated, based on material and surface finish, using the tables below.

LEVEL OF SURFACE FINISH	HOLDING FORCE
GROUND	90-100%
FINE MILLED	60-80%
ROUGH MILLED	40-50%
CAST FINISH	20-30%

MATERIAL	HOLDING FORCE
NON-ALLOY STEEL 0.1-0.3% C	100%
NON-ALLOY STEEL 0.4-0.5% C	90%
NON-DISTORTING ALLOY STEEL	80-90%
GREY CASTING	40-60%
NON-DISTORTING ALLOY STEEL HARDENED TO Rc 55-60	30-50%
AUSTENTITIC STAINLESS STEEL, BRASS, ALUMINUM, COPPER	0%

VACUUM CHUCKS In theory 14.7 PSI can be obtained with a vacuum chuck.  In the real world, under ideal conditions, using a ground workpiece with all unused holes completely masked off a MAXIMUM of approximately 10 PSI can be obtained.  Dirt, warped parts, a rough surface finish and other factors can reduce this significantly.