Let’s just put it out there. Valve failures are the biggest cause of unscheduled compressor shutdowns, which can be costly in terms of production and manpower losses, and valve springs are the biggest cause of those failures. Therefore, controlling costs of an unscheduled shutdown due to mechanical failure means creating longer-lived compressors and that, in turn, means developing stronger, better springs.
In reciprocating compressors, springs are used to control the timing of the valve closing. Because the valve motion includes rapid acceleration and deceleration, it creates high stress on the spring and contributes to earlier-than-expected spring failure.
Small But Strong
With a variety of options for size, shape, function and material, let’s take a look at some of the advantages of using music wire to make compression valve springs. Music wire is a high-quality spring wire that is very pliable and better able to handle high stresses under repetitive loading than other spring materials.
Made from tempered, high-carbon steel, this wire was originally developed for use as piano wire, hence its name. Playing the piano is a demanding use of the wire, which calls for high tension, repeated blows and stretching and slackening of the wire for tuning purposes. On top of that, it is expected to last many years and withstand indefinitely the repeated stress of pianists at work.
Because of its strength and durability, music wire is used in a variety of ways today, including production of compressor valve springs, visual effects for stage and screen and in surgical situations. Today’s music wires are formed from metals and alloys, including brass, copper aluminum or stainless steel, in varying thicknesses.
Piano wire is also unique from other wires because it has no twist and is not made up of groups of smaller-diameter wires. It is due to all of these properties that music wire is used to make springs for industrial applications.
Treatments to Make Springs Stronger
A common problem with compressor valve springs is corrosion from caustic gases and liquids and by itself, piano wire is unable to withstand extreme temperatures. However, there are several surface treatments that can be applied to make the springs more durable.
- Magnetizing
- Metallic plating
- Grinding
- Painting
These treatments, including treatments for heat and stress relief, can be applied to ensure the compressor valve springs meet the demands of your production environment.
A trusted spring manufacturer should be able to discuss what type of material would work best for your compressors. Along with music wire, materials such as stainless steel, beryllium copper, phosphor bronze, chrome silicon and more are available in thicknesses from 0.005 inches to 0.120 inches. Each material has different properties, such as elasticity, yield, fatigue and creep strengths, so there are many options to help you get a great fit.
Test Your Design
Your manufacturer should also conduct mechanical and strength calculations to help you design a spring that fits your needs. To help determine its performance, a prototype should be tested in a simulated environment, which gives you the opportunity to learn first-hand how it will react its intended environment.