- Huyett Marketing Department
- 03/11/2021
What is a Taper Pin?
A taper (tāpər) pin, or tapered pin, is a cylindrical pin with a diameter that gradually decreases over a given length. Taper pins can be manufactured from carbon steel, alloy steel, Monel, and a variety of stainless steels. Taper pins are commonly used in low torque, precision positioning and locking applications. They can be found in printing presses, gear hubs, and other mechanical assemblies.
What are the Different Features of a Taper Pin?
Taper pins are distinguishable by the gradual decrease of diameter over the length of the pin. Additional features include measurement type, head type, material, microfinish, and finish.
Taper
is the gradual decrease in thickness of the pin. While custom applications exist, the common rise over run of inch taper pins is 1/4 inch rise for every 12 inches of length and 1mm rise for every 50mm of length for metric pins.
Measurement type
for taper pins consists of either inch (imperial) or metric. Knowing if a taper pin is metric or inch is important as reference points for measuring diameter and length differ slightly.
Head types
can be categorized by three common styles: standard, internal thread, and external thread.
- Standard taper pins are simple in design with each end featuring a slight radius. Standard taper pins are intended for through‑hole applications so that they can be driven out with a hammer and punch.
- Internal Threads have tapped threads in the large end of metric and inch taper pins. The internal threads allow the taper pin to be installed into blind holes while providing a means for removal with the assistance of a bolt and slide hammer. These pins are ideal in blind hole, low clearance applications.
- External Threads are machined on the large end of the taper pin. They often provide an anchor for removal; however, they can also be used for attaching additional parts of an assembly. External threads can be found on metric and inch taper pins and are great for applications without low clearance restrictions.
Standard Taper Pin
Internally Threaded Taper Pin
Externally Threaded Taper Pin
Materials
used to make taper pins vary widely. Taper pins are crafted from alloy steel, carbon steel, Monel, 12L14 steel, and various stainless steel grades.
- Carbon Steel is primarily a combination of iron and carbon, with carbon content ranging from .05% up to 3.8%. Carbon adds hardness to the metal, and as a result, lowers ductility and makes the material harder to machine. Carbon steel offers minimal corrosion resistance and should be zinc plated or coated with some other medium that can withstand various environmental conditions.
- Alloy Steel is a variation of carbon steel; however, it has relatively high percentages of other elements including manganese, nickel, titanium, copper, and others. Alloy steel is more resistant to corrosive materials than carbon steel; however, it can be coated or plated by special request if an application calls for it.
- Monel , which is also known as Monel 400, is a trademarked name often used when referring to a cupronickel alloy known as alloy 400. Monel is made up of roughtly 63% nickel and 28‑34% copper. This alloy provides good ductility, thermal conductivity, corrosion resistance, and performs great at low temperatures.
- Stainless Steel, sometimes called corrosion‑resistant steel (CRES) is a steel alloy with a minimum of 11.5% chromium. This added level of chromium provides enhanced corrosion resistance, making stainless steel a great material for applications exposed to salt water, chemicals, and other corrosive agents.
- 12L14 is a cold drawn carbon steel that has been resulphurized and rephosphorized. The added sulphur, phosphorus, and lead elements give 12L14 high ductility and easier machinability. However, due to the lower carbon content, overall strength is lower than other cold drawn carbon steels.
Microfinish
is a key, critical feature of taper pins. Microfinish, or microfinishing, is the abrasive process that removes even the most miniscule surface imperfections caused by pre‑process manufacturing. Taper pins are run through this process until they have a 63μ microfinish, enhancing lubricity and allowing for smoother insertion into holes.
Finish
of carbon steel taper pins include plain, zinc yellow, and zinc clear. The added zinc coatings provide additional protection against corrosive environmental elements.
How do I Measure a Taper Pin?
To measure a taper pin, first identify if the pin requirements in question are metric or inch (imperial).
Measuring metric taper pins is a straight forward process. For standard, internal, and external thread metric taper pins, measurements can be acquired by measuring the small end of the pin for the diameter. Pin length is realized by measuring the pin end to end.
There is a little more variation measuring inch taper pins as compared to their metric counterpart. Standard and internally threaded taper pin diameters are measured from the large end of the pin, and their effective lengths are measured from end to end. Externally threaded taper pin diameters are measred at the widest point just before the taper transitions to the threaded tang. Its length is also measured from this point to the small end of the pin, thus excluding the threaded portion of the pin from the effective length.
What Do the Numerical Designations for Taper Pins Mean?
Lastly, inch taper pins can feature specific designations. These are called out by numbers that refer to the diameter of the large end of the pin. Visit the conversion chart below for a simple, efficient way to cross reference fractional and decimal diameters to numerical designations.
