Kemmler 4.5° Shrink Fit Chucks with Coolant Channels

Available Sizes and Part Numbers

Purpose and Application

Kemmler shrink fit chucks with coolant channels are designed for high-performance milling on CNC machines with SK 40 and SK 50 spindle tapers (ISO 7388-1 / DIN 69871). Using chucks with integrated coolant supply channels resolves effective chip removal and cooling issues when machining deep shoulders, difficult-to-cut steels, titanium, and heat-resistant alloys where external coolant supply is blocked by workpiece cavity walls.

Design and Features

The primary design advantage of this series is longitudinal internal channels machined directly into the chuck body along the clamping bore. Pressurized coolant is supplied parallel to the tool shank and exits right next to the cutting edges. The chucks retain all advantages of solid thermal clamping: radial runout ≤ 3 µm, symmetrical clamping, and high dynamic stability (G 2.5 at 25,000 rpm). Re-clamping is performed using standard induction or contact shrink fit units.

Compatibility

Tooling is compatible with SK 40 and SK 50 spindles (ISO 7388-1 / DIN 69871). Designed for clamping solid carbide (HM) tools with h4 tolerance (for 3–5 mm diameters) and carbide/HSS tools with h6 tolerance (for 6–32 mm diameters). Spindle retention is achieved via ISO 7388-3 pull studs (formerly DIN 69872).

Selection Parameters

Selection is based on SK spindle taper (40, 50), shank diameter (from 3 to 32 mm), and projection LPR:

• Standard Modifications: projection LPR = 80 mm, 100 mm;
• Extended Modifications: projection LPR = 120 mm.

Key Advantages

• Direct Coolant Delivery to Cutting Zone: integrated channels provide forced cooling and chip flushing even in deep cavities.
• Extended Tool Life: reduced thermal load on the cutting edge significantly decreases wear during heavy-duty and high-speed operations.
• Precision Accuracy: radial runout ≤ 3 µm guarantees accurate dimensions and stable milling.
• High-Speed Balancing: class G 2.5 at 25,000 rpm reduces vibration and protects the machine spindle unit.
• Maximum Clamping Force: solid thermal shrink clamping prevents tool slippage under high loads.