Compression Springs

Outside Diameter, Mean Diameter, and Inside Diameter:

Outside Dia. is the most common and easier to measure. Inside Dia. is often listed if a spring must work over a rod or raised 'cap'.

Mean Dia. is common on older prints and useful when a spring works where both the inside and outside of the spring are restricted like a hole and rod. It is best to list anything the spring works over or inside of so your spring manufacture can look for conflicts, Springs change diameter when being used!

At least 1 is needed in almost every application.

Diameter:  Outside inch   Mean inch   Inside inch

         or          Rod inch  and/or  Hole inch

Load or force: Load or force:

The purpose of most Compression springs is to provide a force at a certain length. Specifying an example like at 3 inches long to have 14 lbs or when 76.2mm long to have 30.8kg . If you know this or even just the length, it is best to give that so that the spring best matches you needs.

  If know, the spring is used at the Length inch  and the Load lbs

              other: the spring is used at Length inch  and the Load lbs

              other: the spring is used at Length inch  and the Load lbs

Rate, factor (k) or spring constant:

As a spring is compressed its force increases. The ratio between Force and Deflection is the rate. The rate always has two units like pounds per Inch (#/” or Lbs./in), Kilograms per mm (kg/mm), or other similar ratio.  In old specifications the rate could be called out simply in pounds, where the default was per inch.  A spring with a 15Lbs./in. rate if deflected 1 inch would have 15Lbs. of force. Deflected 2 total inches would have 30 Lbs.

Spring Rate lbs /inch  (default or list your unit in the rate box.)

Number of Coils:

The Active coils determine the rate of the spring, but is not the best way to specify a quality spring. But if you do not have the rate or a load at length above then it is sometimes the only way. Old prints often just list coil count. The Total coils is all coils even if they do not have space for deflecting, or are ground on.

Active Coils   Total Coils

Less desirable is a measure for the way the coils are pitched. this if not very consistent nor very accurate, but also is shown on older prints and specifications.

   Pitch inch   Space inch

Free Length, Over All Length(OAL), and Spring Length:

This is the length the spring is in an unloaded length like while sitting in your hand, or on a table or in a box.

Free Length inch (s)

Type of Ends: Type of Ends:

4 main types of ends

   Closed Ends Not Ground Closed Ends Ground  (most common)


      Open Ends Ground (rare)                Open Ends Not Ground

Also special ends might be used, enter that here.

Default - Closed Ends Ground

Addtional Information: Springs already on prints or specified might already list the wire.

Wire Size inch  and Material Type

Quantity - How many pieces would you like quoted? We can do 1 to hundreds of thousands