In Turkish production of hydraulic valve bodies, pump housings and complex cast or machined parts, blind-hole tapping is one of the most common – and most painful – operations. When a tap breaks in a blind hole, the part is usually scrapped and, in many cases, the machine sits idle while operators try to remove the broken tool or reset the job.

Field investigations show that in many cases the material is not “too difficult,” but the tap geometry and chip evacuation strategy do not match the blind-hole application. Typical patterns include:

• Straight flute taps, designed mainly for through holes, being used in deep blind holes where chips are compressed at the bottom;

• Deep blind holes being tapped at the same speeds and feeds as shallow through holes, leaving little safety margin;

• Insufficient or inappropriate cutting fluid supply, causing chip adhesion and flute blockage.

Spiral flute machine taps are designed as a targeted upgrade for this type of work. By using a 30–40° spiral flute, these taps actively pull chips up and out of the hole, reducing chip packing at the bottom and the associated torque spikes that often lead to breakage.

Spiral Flute Blind-Hole Tap – Main Parameters (Example)

To make spiral flute taps truly deliver value in Turkish workshops, a few selection and usage points are critical:

1. Understand hole depth and effective thread length
   For deep blind holes, choose a suitable spiral angle and chamfer form, and always leave a safety distance at the bottom to avoid “bottoming out” the tap.

2. Match substrate and coating to material
   For standard structural steels, HSS-M2 with TiN is often sufficient. For harder or alloyed steels, a higher-grade substrate and more advanced coating may be justified to stabilize tool life.

3. Adjust tapping strategy
   For deeper holes, using a slightly lower cutting speed, generous cutting fluid flow and, where applicable, peck or cycle tapping can significantly reduce peak torque and breakage risk.

Once through-hole and blind-hole applications are separated by geometry and supported by appropriate cutting data and lubrication, blind-hole breakage rates in Turkish workshops typically drop dramatically. Tool life becomes more predictable, machine utilization improves, and delivery commitments to end customers become easier to keep.