Value Collection 204-4020 ER40 Collet 5/16 Inch

Product Description

The VALUE COLLECTION 204-4020 is an ER40 series collet designed for use in CNC machining centers, milling machines, and other rotating spindle equipment that accept ER40 toolholding systems. This collet has a decimal inch bore size of 0.3122 inches, corresponding to a 5/16 inch nominal tool shank diameter. It holds tool runout to a total indicator reading (TIR) of 0.0005 inches, which supports accurate, repeatable cutting performance in production and job-shop environments. Machinists and toolroom technicians install this collet as part of a standard ER40 collet chuck assembly.

This collet is suited for use in both manual and CNC milling, drilling, tapping, and light turning operations wherever an ER40 collet chuck is mounted. The 0.3122 inch bore accepts standard 5/16 inch round shank cutting tools including end mills, drills, reamers, and taps. It is appropriate for light to medium-duty material removal in a shop or industrial production setting. The low TIR rating makes it a practical choice for applications where tool accuracy directly affects finished part quality.

Key Features

• ER40 collet series for use with ER40 collet chucks and toolholders
• 0.3122 inch decimal bore accepts 5/16 inch nominal shank tools
• 0.0005 inch TIR for accurate, low-runout tool holding
• Weighs 0.55 pounds — lightweight and easy to handle during toolchanges
• Single-piece packaging suitable for individual replacement or small inventory replenishment

Compatibility

Designed as a standard ER40 collet for use in any ER40-compatible collet chuck or toolholder accepting a 5/16 inch bore collet.

Installation Notes

ER40 collets are installed and removed by machining technicians using an appropriate ER40 collet nut and spanner wrench matched to the chuck body. The spindle or machine tool must be fully stopped and locked out before changing collets. Inspect the collet bore and chuck taper for chips or damage before seating the collet to avoid compromising TIR. Never exceed the manufacturer-rated speed or clamping torque range for the collet chuck assembly in use.