DIN 69871 SHRINK FIT HOLDER_69871-SC-S

Standards

• Taper shank to DIN 69871, form AD/B (central coolant supply; coolant holes in the collar are closed with releasable headless screws on delivery)
• Tool shank tolerance: Ø3, 4 and 5 mm h4; Ø6 to Ø32 mm h6 (69871-SC range)

Material and balancing

• Alloy case-hardened steel, HRC 60 ± 2 (HV 700 ± 50), hardening depth 0.8 mm ± 0.2 mm
• Pre-balanced G 6.3 at 15,000 rpm; G 2.5 fine balancing at extra charge

Cautions

• Holders with Ø3, 4 and 5 mm bores must be used with solid carbide tool shanks only.
• Suitable for induction, contact and hot air shrink units.
• Clean the bore and the tool shank before shrinking; oil or dirt reduces clamping force.
• The holder is hot after shrinking: wear heat-resistant gloves and let it cool completely before use.
• A pull stud matching the machine spindle is required (Dormer Pramet PS-69872 range).

Overview

The Dormer Pramet 69871-SC range is a family of shrink fit holders with a DIN 69871 taper shank. Model 69871.40ADB-SC.03.080.S has an SK 40 taper in form AD/B, a Ø3 mm shrink-fit bore and an 80 mm protruding length. The holder grips the tool by thermal expansion: the bore is heated, the tool is inserted, and the bore contracts as it cools to clamp the shank around its full circumference.

Key features

• DIN 69871 SK 40 taper shank, form AD/B: supplied as form AD (central coolant), with the form B coolant holes in the collar closed by releasable headless screws
• Ø3 mm bore for solid carbide tool shanks with h4 tolerance
• Slim nose: body diameter 11 mm at the nose and 15 mm at the rear, with a 4.5° body half taper angle for good access in deep cavities
• Alloy case-hardened steel, surface hardness HRC 60 ± 2, hardening depth 0.8 mm ± 0.2 mm, blackened and fine ground
• Pre-balanced to G 6.3 at 15,000 rpm; G 2.5 fine balancing available at extra charge
• Suitable for induction, contact and hot air shrink units

Applications

For holding straight-shank solid carbide tools such as small end mills, drills and reamers in milling, drilling and finishing on CNC machining centres and milling machines with an SK 40 (DIN 69871) spindle.

Shape: one-piece shrink fit holder. On the machine side is a DIN 69871 SK 40 steep taper (7:24) shank with gripper flange and drive slots (form AD/B). This is followed by a slim conical body that narrows at a 4.5° half angle towards the nose and ends in the Ø3 mm shrink-fit bore.

• d (clamping bore): 3 mm
• A (protruding length): 80 mm
• D (body diameter at the nose): 11 mm
• D1 (body diameter at the rear): 15 mm
• Body half taper angle: 4.5°

How to choose

• Spindle interface: this holder fits SK 40 spindles to DIN 69871. For MAS 403 BT spindles, choose the Dormer Pramet BT-SC series instead.
• Tool shank: choose a bore equal to the tool shank diameter. The Ø3 mm bore takes solid carbide tools with Ø3 mm h4 shanks, such as micro end mills, small drills and reamers.
• Reach: the 69871-SC range also offers Ø3 mm holders with 120 mm and 160 mm protruding length (69871.40ADB-SC.03.120, 69871.40ADB-SC.03.160) for deeper features. Choose the shortest length that clears the workpiece for maximum rigidity.
• Coolant: if coolant channels are needed, the 69871-SC-C version is available from Ø6 mm.
• Balancing: standard G 6.3 at 15,000 rpm; G 2.5 fine balancing can be ordered for high-speed finishing.