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ER32 Collets


  • Architecture: interleaved spring collet
  • Steel : SCM440
  • Hardness: HRC 46
  • Taper: 8°
  • Surface Roughness: Rz 2.5
  • Internal hole by boring machine.
  • Collet Tolerance Grades:(read the Collet Selection tutorial)
    • EP (extreme-precision grade) TIR < 0.0001in (0.0025mm)
    • UP (ultra-precision grade) TIR < 0.0002in (0.005mm)
    • PG (precision grade) TIR < 0.0004in (0.01mm)
  • Clamping range ER11= 0.020" (0.5mm), ER16, 20, 32, 40 = 0.039" (1mm )
  • Compatible with DR, RD, ESX, AR, & BR Series Collets
ER-25 Ultra-precision collet

Generally speaking, collet manufactures specify a single value for the runout (TIR) of a collet. Often it is not clear where, relative to the collet face, the measurement was made. International standards for ER style spring collets (DIN6499 and ISO15488) specify that the TIR of a collet should be determined at the collet face and at a distance not less than 4 times the clamping diameter (D). For example, the TIR of a collet with a clamping diameter of 1/8" (3.18mm) should be measured as close to the face as possible and at a distance not less than 4 X 1/8" = 1/2" (12.7mm) along a certified precision calibration blank.

The measurement reported is generally the one taken at the 4 X D point on the blank. No mention is made of the other measurement, or the phase angle between them. Without these 2 pieces of infomation, there is no way to determine what the TIR will be farther from the collet face. It may not souund like much of a problem but, if the two measurements are exactly 180° out of phase, a tool clamped in the collet will be skewed across the central axis with the TIR increasing the farther you get from the crossing point. For collets used with microtools (like ours), it is more important to know how the tool is "wobbling" at the length where it is actually cutting. For 1/8" shank bits with an overall length of 1-1/2", this is typically about 1" from the collet face.

For that reason, we denote our collet grades with a TIR specified at the collet face (TIRF) AND at a point 1" down the calibration blank (TIR1") as shown in the image on the left. These values are listed in the table on the right.

Grade TIRF TIR1"
EP
(Extreme-Precision)
0.0001"
(0.0025mm)
0.0003"
(0.0076mm)
UP
(Ultra-Precision)
0.0002"
(0.0051mm)
0.0004"
(0.0102mm)
PG
(Precision-Grade)
0.0004"
(0.0102mm)
0.0008"
(0.0204mm)
SG
(Standard-Grade)
0.0010"
(0.0254mm)
0.0015"
(0.0381mm)
TIR
  • low noise operation
  • longer tool life
  • more accurate cutting and higher kerf fidelity
  • compatible with carbide microtools
ER-25 Ultra-precision collet
Collet Range Shank
1/8 .086-.125" 1/8"
5/32 .117-.156" 5/32"
3/16 .148-.187" 3/16"
7/32 .179-.218" 7/32"
1/4 .211-.250" 1/4"
9/32 .242-.281" 9/32"
5/16 .273-.312" 5/16"
11/32 .304-.343" 11/32"
3/8 .336-.375" 3/8"
13/32 .367-.406" 13/32"
7/16 .398-.437" 7/16"
15/32 .429-.468" 15/32"
1/2 .461-.500" 1/2"
17/32 .492-.531" 17/32"
9/16 .523-.562" 9/16"
19/32 .554-.593" 19/32"
5/8 .586-.625" 5/8"
21/32 .617-.656" 21/32"
11/16 .648-.687" 11/16"
23/32 .679-.718" 23/32"
3/4 .711-.750" 3/4"
ER-25 Ultra-precision collet

Collet Type Collet Size Grade / RunoutReviews Part Number Price
ER32 0.1250" (3.175mm) PG / 0.0004" ERPG-ER32-1250

$25.95

ER32 0.1875" (4.76mm) PG / 0.0004" ERPG-ER32-1875

$25.95

ER32 0.2500" (6.35mm) PG / 0.0004" ERPG-ER32-2500

$25.95

ER32 0.3750" (9.53mm) PG / 0.0004" ERPG-ER32-3750

$25.95

ER32 0.5000" (12.70mm) PG / 0.0004" ERPG-ER32-5000

$25.95