Do you know the key differences between a Single Form Thread Mill and a Multi-Form version? Do you know which tooling option is best for your job? This blog post examines how several factors, including the tool’s form and max depth of thread, are important to ultimately making the appropriate Harvey Tool decision.

Thread Mill Product Offering

Single Form

The single form thread mill is the most versatile threading solution Harvey Tool offers. These tools are ground to a sharp point and are capable of milling 60° thread styles, such as UN, metric, and NPT threads. With over 14 UN and 10 Metric sized tools, Harvey Tool’s single form selections allow machinists the opportunity to machine many different types of threads.

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Single Form Thread Mills for Hardened Steels

Similar to the standard single form, Harvey Tool’s thread mills for hardened steels offer machinists a quality option when dealing with hardened steels from 46-68 Rc. The following unique geometries helps this tool machine tough alloys:

1. Ground Flat – Instead of a sharp point these tools have a ground flat to help ensure long tool life.
2. Eccentric Relief – Gives the cutting edges extra strength for the high feeds at relatively low RPMs required for harder materials.
3. AlTiN Nano Coating – Allows for superior heat resistance.

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A key difference between the standard Single Form and the Single Form for Hardened Steels is that the tools for hardened steels are actually only capable of milling 83% of the actual thread depth. At first, this may seem detrimental to your operation. However, according to the Machinery’s Handbook 29th Edition, “Tests have shown that any increase in the percentage of full thread over 60% does not significantly increase the strength of the thread. Often, a 55% to 60% thread is satisfactory, although 75% threads are commonly used to provide an extra margin of safety.” With the ability to preserve tool life and effectively perform thread components, Harvey Tool’s single form thread mills for hardened steels are a natural choice when tackling a hardened material.

Tri-Form

Tri-Forms are designed for difficult-to-machine materials. The tri-form design reduces tool pressure and deflection, which results in more accurate threading. Its left-hand cut, left-hand spiral design allows it to climb mill from the top of the thread to the bottom.

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Multi-Form

Our multi-form thread mills are offered in styles such as UN, NPT, and Metric. Multi-Form tools are optimized to produce a full thread in single helical interpolation. Additionally, they allow a machinist to quickly turn around production-style jobs.

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Coolant-Through Multi Form Thread Mills

Coolant-Through Multi Form Thread Mills are the perfect tool for when a job calls for thread milling in a blind hole. The coolant through ability of the tool produces superior chip evacuation. These tools also improve coolant flow to the workpiece – delivering it directly from the tip of the tool – for decreased friction and high cutting speeds.

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Long Flute

These tools are great when a job calls for a deep thread, due to their long flute. Long Flutes also have a large cutter diameter and core, which provides the tool with improved tool strength and stability.

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N.P.T. Multi-Form

While it may seem obvious, N.P.T. Multi-Form Thread Mills are perfect for milling NPT threads. NPT threads are great for when a part requires a full seal, different from traditional threads that hold pieces together without the water-tight seal.

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