Pipe Thread Forming Taps

Pipe Thread Forming Taps

Pipe thread forming taps (also called roll-form or fluteless taps) cut threads by displacing material rather than removing it as chips. The tap presses a cold-worked thread into the workpiece, producing a stronger thread than cutting taps and eliminating the chip-management problems that plague some tapping operations. AIMS Industrial stocks pipe thread forming taps in BSPF for ductile materials and applications where chip-free threading is the priority.

How thread forming works

A thread forming tap has lobed cross-section instead of cutting flutes. As the tap rotates into a pre-drilled hole, the lobes plastically displace the workpiece material, cold-forming a thread profile. The work-hardened, displaced material gives the formed thread a fatigue strength typically 25-50% higher than an equivalent cut thread. There are no chips to evict, which simplifies chip management and prevents the chip-related problems (jamming, breaking) of cutting taps.

Where thread forming earns its place

• Ductile materials — aluminium, copper, brass, mild steel, and ductile stainless that can plastically deform
• Chipless threading requirements — applications where chips would contaminate the system (food, pharma, hydraulic)
• Stronger thread requirement — threads that need to handle higher fatigue loads or vibration
• Blind holes in ductile material — no chip-evacuation problem since there are no chips
• Production tapping — fewer tap failures and longer tap life than cutting taps in suitable materials

Where NOT to use thread forming

Hard or brittle materials (cast iron, hardened steel, unannealed bronze) crack rather than deform — thread forming taps don't work in those materials. Materials with hardness above about 30-35 HRc are usually beyond the practical range. For those, stick with cutting taps.

Drill size — different from cutting taps

Thread forming taps need a different drill size than cutting taps. Because the material is displaced rather than removed, the starting hole needs to be slightly larger than for a cutting tap of the same nominal size. Manufacturer drill charts specify the right size for the tap and material — using a cutting-tap drill chart with a forming tap leads to over-tight tapping torque, premature tap failure, or stripped threads. Always check the chart for the specific tap.

Lubrication

Thread forming generates significant heat from cold-working the material. A specialist forming-tap lubricant (or heavy-duty cutting fluid) is essential — running dry kills the tap quickly. Some manufacturers specify particular lubricant grades for their forming taps; check the data sheet.

Brands stocked at AIMS

Sutton Tools, Bordo, and Champion cover the pipe thread forming tap range in HSS-E (cobalt) for the ductility and toughness forming work demands. For specialty applications or non-standard sizes, contact our team for sourcing.

Need help deciding between cutting and forming taps for a specific application? contact our team — we'll work through material, hole type, and tap selection.