Which Wear Resistant Coating Is Right For You?

In today’s competitive marketplace the ability to increase the service life of your equipment while reducing repair and maintenance costs can add significant benefits to your operation. Whether you are in mining or industrial manufacturing, margins are progressively being pushed. Simply knowing that a wear resistant coating should be employed is not enough. A coating poorly matched to an application can result in early failure of the lining resulting in significant wear.

With this in mind then, how does one choose a coating that will offer the best service life and maximise return on investment?

First a disclaimer. All recommendations listed here, are just that. The only true way to evaluate a coating is through real world testing in your process. However that isn’t very helpful, nor does it offer any solutions. So the recommendations to follow, should be seen as a guide in how you can expect coatings to act under certain conditions with a high degree of reliability.

Don’t take this as gospel, and most certainly expect this post to be updated from time to time. As we encounter new situations or exceptions to what we have previously advised, we will document it and post it for your benefit.

Polyurethane Vs Rubber

The following ready reckoners can be applied to Metaline 700 series urethanes

  • when water is available for cooling and lubrication¬†urethane thickness can be reduced to between 30-50% of that of rubber
  • ¬† in dry environments thickness needs to be increased to around 80% of rubber thickness to allow for increased material to act as a heat sink (when urethane flexes and rebounds, it is not 100% efficient and some energy is released as heat)
  • repairs to either Rubber or Urethane can be completed much faster with a spray urethane than relining in rubber. The repair should also have superior wear resistance. Check Chemical and Temperature resistance to ensure compatibility.
  • ¬†As Urethane can be sprayed, it is able to form a seamless coating encapsulating the whole surface without any seams or joins. For complex surfaces this can offer a significant advantage in reliability, as seams and joins are always a weak point.

Polyurethanes and Ceramics approach wear reduction from opposite ends of the septum, one absorbs the impact and returns the energy without being damaged, the other resists wear by being so much harder than the wear product. This fundamental difference means that each product will have its niches where it endures so much better than the other.

Polyurethane V’s Ceramic Polymer

  • Polyurethane works well to about 80C wet and 130C dry. Ceramic top out at much higher rates. Loctite High Temp Ceramic will offer protection to 280C.
  • Chemical resistance is almost always stronger in the Ceramic products, as always there are exceptions.
  • Ceramics need to be matched to the wear particle size. Ceramic Epoxies function best when the average wear particle size is around the same as the ceramic particle. Where the wear slurry/solution is has particles that are smaller than the ceramic particles, the ceramic won’t wear, however the composite matrix that holds the ceramic particles together will be eroded. In these instances, especially when combined with high velocity slurrys, will result in rapid wear. This is why it is important to select a ceramic product with the correct slurry handling characteristics.
  • While poor surface preparation and poor application will limit the performance of both products, the ceramics are less demanding than the urethanes. In controlled environments this has little impact, but when considering site works it may offer advantages in certain instances.
  • If heavy Impact is to be endured classical sense would advise that urethane is the only option. However ceramics with semi flexible bonding agents offer an alternative, price, service life, temperature, chemical resistance all need to be considered.
  • Due to Urethanes flexibility 75 metres per second is the maximum speed before the coating is unable to support itself. Ceramics by their very nature offer a higher speed resistance.
  • Urethanes can offer wear protection while offering either high or low coefficients of friction. Urethanes can also be modified with silicon additives to further reduce fiction.

Cost is dependent on a number of factors not limited to

  • coating thickness – each product will require a certain minimum thickness to achieve an acceptable outcome. Depending on the application one may be thicker than the other.
  • Cost per volume of cured product.
  • Cost to apply the product

Often the cost two competing products is compared only on the price difference between them. Just picking the cheapest option may result in increased costs over the life of a coating. It is alway important to consider the total cost of ownership over the lifetime of a coating. In its simplest form the cost of the two repair methods should be divided by the expected service life of the repair. This results in a cost per unit of time that allows you to clearly cost both repairs.