Northwest Sleeve Inc.
12410 SE 282nd Avenue, Suite E
Boring OR, USA 97009
Phone: 503.666.8430
Toll Free Order Line: 877.753.3830
E-Mail: sales@nwsleeve.com

Northwest Sleeve Custom Engineering

OUR TOP SECRET FORMULA

We won't tell you the secret to our success, but we will share what we can about the properties of our material and why they are extremely important to the foundation of our sleeves.

CAST IRON
Cast iron is defined in categories based, in part, on the percentage of carbon and silicon in the heat. Class 40, 50 and 60 gray irons are defined by composition and properties, including machinability, elasticity and tensile strength.

Our formula is based on Class 45 gray iron with strict management of carbon and silicon and other baseline elements. We then add alloying elements such as nickel, chromium, molybdenum and copper to increase strength and obtain important properties such as higher heat resistance, wear resistance, friction reduction and oil retention. Alloying the iron is critical, but is the "overall process" that gives us the final results we require.

 

HARDNESS
Brinell hardness (BHN) is the standard measurement for cast irons. Our BHN range is 227 - 240. Our peers publish their BHN from 190 - 210. The higher the number, the harder the iron. 190 is soft enough for rings to create a ridge in the sleeve; 260 is almost impossible to put a carbide porting tool through.

 

HEAT TREATMENT
Since we engineer our formula and control the foundry process to create the appropriate BHN and grain structure, it is not necessary for us to heat treat our rough castings. Other foundry processes require heat treatment which can change the molecular structure of the iron as well as soften the iron. Although these are accepted processes, we do not like the degradation of grain structure we see when this type of process is applied. Grain structure is critical to hardness and oil retention.

 

DUCTILE
Ductile can be close grained and hard like our custom cast, but the characteristics of ductile are NOT ideal for general sleeve application:

1). Ductile takes twice as long to dissipate heat than does gray.
2). The nodular micro-structure does not retain oil well.

Our Class 45 is comparable in hardness and strength to good quality ductile (80-55-06) and herein lies the primary reason we do not offer ductile. We do, however, now offer a Class 60 material which sits right at the edge between gray iron and ductile. We use this material primarily in four stroke cylinders where the bore size is more than two millimeters above the standard (OEM) bore. The additional tensile strength and hardness contributes significantly to stabilizing the cylinder while maintaining the integrity of the bore.

 

DOES ANY OF THIS MATTER?
YES! Northwest Sleeves will stand up longer under extreme operating conditions. They generate less friction, reduce ring wear and can safely run "thin wall" applications. (we consider thin wall to be .070" - .080"; average wall thickness for stock replacement sleeves is .140").

YES! All this really does matter to our customers and it's why we continue to put our energy and resources into keeping our quality standards high.