Internal threads are formed by tapping on punched or laser-cut holes, or by using roll taps to form threads directly. Roll forming produces chip-free threads and increases thread strength, making it a standard process for sheet metal fastening holes, widely used in internal support plate fixation and PCB mounting.
Process Overview
Tapping is divided into cut tapping and roll tapping: cut tapping uses cut taps to machine threads, offering high versatility; roll tapping forms threads by displacing metal, producing no chips and offering higher strength and longer life. We perform tapping on CNC machining centers or automatic tapping machines, with pitch and depth controlled by the program. Batch thread consistency is stable, and go/no-go gauge 100% inspection is performed after machining.
Capability Parameters
- Thread Range: M2 – M8 standard sizes
- Machining Method: Cut tapping / Roll tapping
- Applicable Sheet Thickness: ≥ 1.0 mm (requires sufficient engagement length)
- Pitch: Coarse / Fine pitch available
- Inspection: Go/no-go gauge 100% inspection, torque spot check
Technical Key Points
The key to tapping quality is bottom hole size and lubrication: if the hole is too large, threads will be shallow; if too small, the tap may break. We strictly match the bottom hole to the material and pitch. Roll tapping requires higher bottom hole accuracy; we use drilling plus reaming to ensure hole diameter consistency. Specialized tapping coolant is used to reduce tap wear and breakage risk; for thin sheet tapping, backing pads are applied to prevent thread bulging and hole edge deformation.
Typical Applications
Internal support plate fixation, PCB mounting, and heat sink fastening. When parts require standard internal threads and sheet thickness is sufficient, tapping is the most cost-effective joining solution; if sheet thickness is less than 1 mm, engagement length is insufficient, so press-fit nuts or flanged tapping is recommended.
FAQ
Can thin sheets be tapped?
Sheet thickness ≥ 1.0 mm is recommended for direct tapping; thinner sheets have insufficient engagement length and are prone to stripping, so press-fit nuts, flanged tapping, or adding reinforcing ribs is recommended.
How to choose between roll tapping and cut tapping?
Roll tapping offers higher strength and no chips, suitable for gummy materials like stainless steel and aluminum, but requires higher bottom hole accuracy; cut tapping is more versatile and slightly lower in cost. We recommend the suitable method based on material and batch size.
Will threads strip after tapping?
Normally no. We match bottom holes and taps to the material and perform go/no-go gauge 100% inspection after machining. If your assembly requires repeated disassembly/reassembly, roll tapping can be selected to increase thread strength and life.
Need thread machining? Please provide thread specifications and sheet thickness, and we will confirm the process plan and provide a quote.