ER COLLET

The ER collet system is one of the most widely used tool-holding systems in machining and CNC applications. Known for its versatility, strong gripping force, and high precision, ER collets are used to hold cutting tools (like end mills, drills, and reamers) or workpieces securely in place. Below is a comprehensive overview of the ER collet system, including its features, sizes, and applications.

What is an ER Collet?

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Design: ER collets have an 8-degree taper and a slotted design that allows them to compress and grip tools or workpieces securely.
Grip Range: ER collets can grip tools or workpieces within a range of ±0.5mm (or ±0.020 inches) of their nominal size, making them highly versatile.
Material: Typically made from heat-treated spring steel or alloy steel for durability and precision.
Runout: High-quality ER collets offer low TIR (typically less than 0.01mm or 0.0004 inches), ensuring accurate machining.

ER Collet Sizes

ER collets are available in a range of sizes, each designed for specific tool diameters and applications. The most common ER collet sizes include:

ER Collet Size	Grip Range (Metric)	Grip Range (Inch)	Typical Applications
ER8	1mm – 5mm	0.04″ – 0.20″	Micro-machining, small CNC routers
ER11	1mm – 7mm	0.04″ – 0.28″	Precision engraving, small CNC milling
ER16	1mm – 10mm	0.04″ – 0.39″	Small CNC mills, lathes, and engraving
ER20	1mm – 13mm	0.04″ – 0.51″	Medium-sized CNC mills and lathes
ER25	1mm – 16mm	0.04″ – 0.63″	General-purpose CNC machining
ER32	2mm – 20mm	0.08″ – 0.79″	Larger CNC mills and lathes
ER40	2mm – 26mm	0.08″ – 1.02″	Heavy-duty machining and large tools

Key Features of ER Collets

Versatility: A single ER collet can accommodate a range of tool diameters due to its elastic design.
Strong Grip: The 8-degree taper provides a secure hold, even under high cutting forces.
High Precision: Low TIR ensures accurate machining and micromal tool deflection.
Wide Compatibility: ER collets are compatible with a variety of tool holders, nuts, and spindles.
Durability: Made from high-quality materials, ER collets are resistant to wear and deformation.

Applications of ER Collets

Machine tool holder with the cutter using ER32 COLLET system

CNC Machining: Holding end mills, drills, reamers, and other cutting tools.
Lathes and Milling Machines: Gripping workpieces or tools.
Precision Engraving: Used in small CNC routers and engraving machines.
Dental and Jewelry Tooling: For micro-machining and fine detail work.

ER Collet Nuts

ER collets require a corresponding collet nut to secure them in the tool holder or spindle. The nut compresses the collet, allowing it to grip the tool or workpiece. ER collet nuts are available in different styles, including:

Standard Nuts: For general-purpose use.
Hex Nuts: For easier tightening with a wrench.
Low-Profile Nuts: For applications with limited clearance.

ER Collet Sets

ER collet sets are available in various sizes and configurations, typically including multiple collets and a storage case. Common sets include:

Metric Sets: Collets in 1mm increments (e.g., 1mm – 20mm for ER32).
Inch Sets: Collets in fractional inch sizes (e.g., 1/8″, 1/4″, 3/8″).
Combination Sets: A mix of metric and inch sizes.

High-Precision ER Collets

Improve Mechanical Quality
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For applications requiring ultra-high precision, micro TIR or high-preciseER collets are available. These collets are manufactured to tighter tolerances, with TIR typically less than 0.003mm (0.0001 inches).

Online Retailers: Amazon, eBay, AliExpress.
Manufacturers: Rego-Fix, Lyndex, Techniks, and other reputable brands.

Key Considerations When Buying ER Collets

Size: Choose the ER collet size (e.g., ER11, ER16, ER32) based on your tool or workpiece diameter.
Precision: For high-precisework, opt for micro TIR or high-precisecollets.
Material: Heat-treated spring steel or alloy steel collets offer the best durability.
Compatibility: Ensure the collets are compatible with your collet nut and tool holder.