Product Overview

While high-precision collet chucks (like ER or SK) are excellent for finishing and general-purpose work, they rely entirely on friction to hold the cutting tool. During heavy roughing, slotting, or when machining tough aerospace alloys (like Titanium or Inconel), the immense axial forces can cause the end mill to pull out of the collet, instantly ruining the workpiece and potentially destroying the spindle. The DIN 69871 SK SLN Side Lock Arbor (Weldon Holder) provides a foolproof mechanical solution for CNC milling. The holder features a precision H4 tolerance bore and one or two heavy-duty set screws on the side. These screws tighten directly against the flat machined into the shank of a Weldon-style end mill, creating a positive lock that makes tool pull-out or rotation physically impossible.

Key Features & Advantages

• Zero Tool Pull-Out: The side set screw(s) mechanically lock into the Weldon flat on the tool shank. This guarantees absolute security against tool slippage, spin, or pull-out during the most aggressive heavy-depth-of-cut (HDOC) CNC milling operations.

• Maximum Rigidity: Forged from premium alloy steel (such as 20CrMnTi) and case-hardened to HRC 56-60. The solid, thick-walled construction of the arbor body absorbs heavy milling vibrations, preventing chatter and extending the life of your cutting tools.

• High Precision Bore (H4): The internal tool bore is honed to a precise H4 tolerance, and the external DIN 69871 taper is precision-ground simultaneously. We guarantee a maximum Total Indicator Runout (T.I.R.) of ≤ 0.005mm (5 microns), ensuring even chip loads and superior surface finishes.

• Coolant Through (Form AD/B): Available in standard Form AD (central coolant through the pull stud) or Form AD/B (coolant through the flange), delivering high-pressure cutting fluid directly to the cutting edge for improved chip evacuation and tool life.

• Dual Screws for Large Diameters: Arbors with bore sizes of 25mm (1 inch) and larger feature two set screws for maximum holding power and stability on heavy-duty end mills.

• Dynamic Balancing: Pre-balanced to G6.3 @ 15,000 RPM (or higher upon request) to protect your CNC spindle bearings and ensure smooth operation at high speeds.

Why Partner with Pingyuan Zhenghao Machinery?

• Direct Manufacturer Savings: Bypass trading companies and source premium DIN 69871 CNC tooling directly from our factory for highly competitive wholesale pricing.

• Complete Spindle Compatibility: We manufacture the full range of SK tapers: SK30 (for compact mills), SK40 (the industry standard), and SK50 (for heavy-duty machining centers).

• Comprehensive SLN Sizes: Available to fit all standard metric Weldon shank diameters: SLN6, SLN8, SLN10, SLN12, SLN16, SLN20, SLN25, SLN32, and SLN40. (Inch sizes available upon request).

• Strict Quality Control: Every tool holder undergoes rigorous inspection using 3D CMMs, taper gauges (AT3 standard), and dynamic balancing machines before packaging.

Frequently Asked Questions (FAQ) - Selection Guide

Q1: What does "SLN" mean? Is it the same as a Weldon holder?

A: Yes. "SLN" stands for Side Lock Nut (or Side Lock End Mill Arbor), which is the technical term for what is commonly known in the industry as a Weldon Holder. They are designed specifically to hold end mills that have a flat section ground into the side of the shank (a Weldon flat).

Q2: Can I use a regular round-shank end mill in a Side Lock (Weldon) holder?

A:No, it is highly discouraged. If you tighten the set screw against a perfectly round, hardened carbide or HSS shank, it will not hold securely and will likely crush or fracture the tool shank. Side lock holders must only be used with tools that have a proper Weldon flat. For round shanks, use an ER Collet Chuck, a Power Milling Chuck, or a Shrink Fit holder.

Q3: What is the difference between DIN 69871 (SK) and MAS 403 (BT)?

A: While both SK40 and BT40 share the same 7/24 taper angle, they are not interchangeable. The V-flange (the groove where the ATC gripper holds the tool) is located at a different height, and the drive key slots are asymmetrical on SK holders but symmetrical on BT holders. You must use the exact standard your CNC machine's manual specifies.

Q4: Do the holders come with the set screws?

A: Yes, all of our SK SLN Side Lock Arbors come fully assembled with the required heavy-duty locking set screws.

Eliminate tool pull-out and maximize your roughing efficiency on CNC machining centers with our DIN 69871 SK SLN Side Lock End Mill Arbors.

Contact our sales team today for a complete catalog and bulk pricing.