What is the purpose of the flat section on an Extractable Dowel Pin?
The flat section aids insertion and extraction
Extractable dowel pins are precision ground components used in machinery, tooling, and mould making that align parts accurately.
The extractible dowel pin is noticeable due to two key features. These are an internal female thread on one end which aids in the removal of the dowel pin if needed, and a small flat section along its length of the cylindrical body.
This flat surface allows air, lubricants, and hydraulic pressure to escape during installation and removal. The dowel pins are precision ground and very accurate which leaves very little room for air etc to escape.
Preventing hydraulic lock and air trapping
When a precision-ground dowel pin is installed into a hole that does not go all the way through the material, air and lubricants can become compressed and trapped at the bottom.
This trapped air or lubricants can create various issues including the following:
• It can prevent the pin from being pushed fully to its intended depth.
• Push the pin back out after installation
• Can cause unwanted stress on the component walls.
The flat section along the length of the dowel provides a clearance that allows any trapped air, lubricants, and debris to escape as the dowel pin is installed.
Breaking the vacuum during extraction
When removing an extractable dowel pin, pulling it out of a tight blind hole can create a partial vacuum at the bottom of the hole which can resist the easy extraction of the dowel and damage the internal thread of the extractable dowel pins.
The flat section along the length of the dowel pin allows air to entre the hole which allows the pin to be extracted easily.
Maintaining tight precision tolerances
Even though the dowl pin has a small flat section the pin still retains enough outer surface area to ensure the exact locating accuracy and alignment expected from these extractable dowel pins.
Extractable dowel pins frequently asked questions
Can I buy just one dowel pin?
Yes, at Fusion Fixings you can buy just one dowel pin or as many as you need to get the job done, with bulk price discounts across the range
Can you use a standard dowel pin in a blind hole?
Using a standard solid dowel pin in a blind hole does need some kind of air vent hole that allows an escape path for the air. Without this it can cause trapped air or oil to prevent full insertion or push the pin back out.
How do you extract a pull dowel pin?
Extractable dowel pins are specially designed to ensure easier extraction with an internal metric thread on one end. Removal is much easier as a matching screw or specialized dowel pin extraction tool is threaded into the top of the pin, allowing it to be pulled straight out of the hole.
Why are dowel pins hardened and ground?
Hardening improves wear resistance and strength, while precision grinding ensures accurate dimensions and tight tolerances for reliable alignment.
The ranges of dowel pins at Fusion Fixings is growing with quantities from just one to as many as you need to get the job done with bulk price discounts.
