Thread grinding is a method of creating screw threads that utilizes a CNC machine with an abrasive grinding wheel. Compared to other thread manufacturing processes, thread grinding can be used to create incredibly complex and highly accurate thread designs.
The thread grinding process is complex and may vary depending on the specific requirements of the product. As a trusted thread grinding expert, PST utilizes a tried-and-true method that ensures accuracy and quality for all end products.
The thread grinding process consists of several steps from programming to production. PST’s average part cycle time is 10 minutes for this process; however, it may range from as low as 30 seconds up to an hour depending on the part’s parameters.
Before placing product into a thread grinding machine, the required parameters must first be entered. For a new job, CNC programming and set-up can take up to two hours. However, for repeat jobs, the set-up time is minimal since the parameters were previously loaded.
Dressing the Wheel
Once the required parameters are entered, the grinding wheel must be dressed. Within the CNC machine, a diamond wheel is used to dress the grinding wheel to meet the specified requirements.
Dressing the wheel allows the thread grinding process to meet custom tolerances and material requirements. Harder materials require a coarser wheel while softer materials use a finer wheel. This step ensures that the manufactured parts are fragment-free.
Once the wheel is dressed, the first part is placed within the machine. The wheel grinds the form into the part as the machine moves the part horizontally from one end to the other.
PST has external thread grinding capabilities up to 42” in length and 12” in diameter. Threads are ground between centers within the machine; however, if necessary, different holding methods can be tooled and set-up.
PST can also grind parts longer than 42” in length if each part can fit through the thread grinder’s spindle. This process requires multiple setups which ultimately results in additional time and cost.
A notable benefit of the thread grinding process is that it allows thread forming in very hard or brittle materials, which negates any complications from post-thread heat treatment. The thread is ground in the material’s final state, and this provides the best accuracy in thread manufacturing.
Watch PST’s video to see the thread grinding process in action.
Machine accuracy and employee vigilance are critical at PST. When starting a thread grinding project, an associate verifies each individual manufactured piece until the machine consistently produces to-spec product. This process may involve several additional steps and pieces of equipment including:
- Optical Comparator – Projects a magnified part profile on a screen; used to take measurements and check the form of the thread
- Manual Validator – Used to check the lead and lead error of the thread
- Coordinate Measuring Machine – Programmable device used to measure the geometry of a physical object; the part is placed on the table, and a repeatable process is conducted to measure its specific features
- Calibrated Manual Measurements – Calibrated gages and measurement tools are used to check critical dimensions of the threads; when thread gages are not available for measuring pitch diameter, the measurement over wires method is used (PST has a vast inventory of thread wires)
After a thorough single-piece inspection, products are loaded in the machine with confidence. After production, thread ground products are placed into a custom-made shipping container for delivery.
Thread Grinding with PST
PST is a trusted thread grinding partner to organizations in a wide variety of industries. From build-to-print to custom thread grinding, PST can address the needs and specifications for many applications.
PST’s thread grinding offerings include:
- A 3/10ths taper
- A 2/10ths lead tolerance over 12”
- The ability to mate parts
If you’re looking for a thread grinding partner, the experts at PST can help. Contact PST today to learn more.