The Problem: Choosing the Wrong Tap Type

Cutting taps and forming taps look similar but work completely differently. Pick the wrong one and you get packed chips, torn threads or a pilot hole that is simply the wrong size. The choice depends on material, thread depth and the strength you need.

Why It Happens: Two Different Ways to Make a Thread

• Cutting taps remove metal. Straight flute, spiral flute and spiral point taps shear material into chips, so chip control is the main concern.
• Forming (roll) taps displace metal. They press and flow material into the thread form without making chips, so there is nothing to evacuate, and the thread is work-strengthened.

For aluminum, soft gummy material and forming taps usually get along well but can smear if lubrication is poor. For mild steel, both work, and the decision often comes down to blind versus through holes and required thread strength.

The Solution: Match the Tap Type to Material and Hole

• Through holes in mild or carbon steel: a spiral point tap pushes chips ahead and taps fast.
• Blind holes in steel and stainless: a spiral flute cutting tap such as a HSS-G straight / plug tap or the spiral-flute taps listed above lifts chips out and avoids packing.
• Aluminum and ductile metals: a forming tap produces a strong, chip-free thread; a DIN352 HSS-G cutting tap set remains the flexible all-rounder.
• Where thread strength matters most: forming taps work-harden the flanks, giving a stronger thread, but they need a larger pilot hole.

Application: Aluminum and Mild Steel in Practice

In aluminum, forming taps deliver clean, strong threads and eliminate chip problems in blind holes, provided the pilot hole is sized correctly and lubrication is generous. A TiN coated HSSE forming tap survives the higher torque forming demands because its coating reduces friction. In mild steel, cutting taps cover a wider range of threads and materials with less fuss over hole size. Most shops keep both types on the shelf and pick per job rather than standardising on one.

Technical Reference: Cutting vs Forming Comparison

FAQ

Q: Do forming taps need a different pilot hole?
A: Yes, they need a larger blank because they displace rather than remove material.

Q: Are forming taps stronger?
A: The threads are, because forming cold-works the flanks.

Q: Can I use a forming tap in stainless?
A: With care and good lubrication, but cutting taps in cobalt grades are the safer default.

Q: Which is better for high volume?
A: Forming taps for chip-free aluminum, cutting taps for steel; both are used in high-volume shops.

Q: Are forming taps more expensive?
A: They usually cost more per tap, but the chip-free thread and higher strength often justify the outlay in the right application.

Key Takeaways

The tap type should follow the material and the hole. Cutting taps remove material and cover the widest range of threads and metals; forming taps displace material for a stronger, chip-free thread that suits aluminum and ductile metals. Match the pilot hole to the tap type and the choice becomes straightforward.

Choosing Between Cutting and Forming HSS Machine Taps

The material decides whether cutting or forming HSS machine taps are the better fit. For aluminum and ductile metals, forming HSS machine taps produce strong, chip-free threads; for steel and iron, cutting HSS machine taps remain the versatile default. With the pilot hole matched to the type, HSS machine taps deliver clean threads either way.

Pick Your Tapping System

Choose cutting or forming taps to suit your material and holes. Browse the HSS Machine Taps range for both types in the grades and coatings you need.