February 28, 2013by Michael Russo0

It seems like almost every day we will get a phone call in our office from a confused customer concerning bronze casting processes.  In 1911 we began as a bronze foundry and through the years as a casting manufacturer we have become the experts in the various bronze casting methods.    Hopefully this article will help clear up some of the confusion and assist you in choosing the appropriate method for your application.

Let’s begin by describing the 3 most common types of casting processes.  They are sand casting, centrifugal casting, and continuous casting.  Each has their own unique benefits and limitations.

Sand Casting Process

Sand Casting is the oldest of the three.  This process involves making a pattern in the shape of the desired part.  The pattern is then placed in a box called a flask and packed with sand.  A binding agent is added to the sand to help harden it.  The mold is cured and the pattern is removed.  The remaining hollow shaped area is where the molten bronze is poured in order to form into the desired shape.  After the metal cools, the sand mold is removed and you are left with the sand casting.  This casting can be sold as is, or additional finishing processes can follow.

The benefits of the sand casting method is the ability to for special shapes not possible via the other processes.  The disadvantages of sand casting are generally associated with possible impurities in the casting caused by factors including the multiple step process and longer solidifying time needed.



Centrifugal Casting Process


The centrifugal casting process is typically used to cast cylindrical shaped castings.  Centrifugal casting involves a cylindrical shaped mold.  This mold is then rotated or spun about its axis at a predetermined speed.  The castings wall thickness is controlled by the amount of material added during the pouring stage. Due to the nature of the centrifugal casting process the inner diameter of the part must always be round in shape. Most impurities in the metal generally have a lower density than the metal itself.  During the casting process these impurities will collect in the inner diameter of the casting and can be removed during the casting process.  This yields a casting with fewer impurities.

Centrifugal casting advantages include less impurities due to the removal during casting and lower costs associated with the ability to utilize similar molds for different sizes.  The disadvantages are in the limitation on shape of casting and overall length limitations.


Continuous Casting Process

The process of continuous casting bronze is used to cast a continuous length of material.  Molten bronze is cast through a mold from which it takes its profile.  The length of the casting is not determined by the mold, but by a cut off saw. Continuous casting utilizes the force of gravity to help move the metal along.  This casting operation begins high above ground and requires a lot of space.  Continuous casting generally has less material lost than the other forms and a higher productivity rate.  This process also generally yields a superior quality of casting.  This is a result of the faster solidifying time and generally more uniform material properties.   Disadvantages of this casting process are associated with the larger lot size needed to achieve the cost savings.



Where the confusion occurs

I would say around 95% of the confusion experienced by our customers is caused by outdated prints.  When National Bronze Mfg. was founded in 1911, sand casting was the only way to cast bronze parts.  So drawings from that time period will reference sand casting as the method of casting the bronze.  This may be obviously spelled out in the print or may be signified by an ASTM or similar designation.  Since 1911 other bronze casting methods have been developed and proven to be more effective for certain applications, these include both centrifugal and continuous casting.  Unfortunately if a customer is working off a print prior to the development of these methods they may have difficulty finding the correct material.  The reason being is that the material may not be manufactured via the specified process anymore, in lieu of more advanced and efficient processes.  Unless the customer understands what all of the specific designations mean, it is difficult to understand why they cannot locate certain materials.

The best way to determine what casting method is best for your project is to consult with one of our experienced sale engineers.  They will look at the every factor relating to your project and recommend casting methods specific for your individual needs.  To contact one of our sales engineers follow the link below.

Contact a Sales Engineer




February 14, 2013by Michael Russo0

Aluminum Bronze is a broad term for a group of bronze alloys known for their superior combination of mechanical and chemical properties.  Aluminum Bronzes are generally used when standard bearing grade bronze will not withstand specific conditions.  Over the years many aluminum bronze alloys have been given different names, varying from official organization specifications to trademarked brand names from private companies.  In this article I will highlight a few of the most common alloys, list their various names, and describe their ideal applications.

C954 Aluminum Bronze

954 Aluminum Bronze
C954 Aluminum Bronze

This is by far our most often requested alloy of the family.  Aluminum bronze alloy 954 is available in tubing, solid round, and flat bar.  Often referred to as  Wearite 411, and 9C this alloys official designation is CA95400.  C954 Aluminum Bronze is generally continuous cast.  When size requirements exceed the standard continuous cast sizes, centrifugal casting is utilized to manufacture customer specific requirements.  Applications that require C954 Aluminum Bronze include mechanical press bushings, wear plates, and other heavy load applications.


C959 Aluminum Bronze

C959 Aluminum Bronze
959 Aluminum Bronze


C959 Aluminum Bronze is another aluminum bronze alloy that we receive a large amount of requests for quotation.  C959 is available in solid round and flat bar.  Common trade names for C959 are  Wearite 413.  The official copper alloy designation is CA95900.  This alloy is often used the die industry in various press components.

These two aluminum bronze alloys are our most popular of the alloy family.  We also supply many customers with other aluminum bronze alloys specific to their application.  To find out what alloy is best for your application, click the link below.

Click here to discuss aluminum bronze alloy options with one of our trained sales engineers.

Click here to view more information on aluminum bronze alloys.

February 13, 2013by Michael Russo0

As a leading manufacturer of bronze sleeve bushings, we often receive requests for a variety of product types.  A common product request is for self lube bushings.  This term can reference a number of different products.  This article should help you better define your request.

Oil Impregnated Bushings
Oil Impregnated Bronze Bushing

The term “Self Lube Bushings” is a broad term for various self-lubricating products.  In a general sense it refers to a bronze bushing that does not require manual lubrication. There are several methods used to achieve this characteristic, below are the 2 most common.

Oil Impregnation- These are bronze bushing manufactured through the powdered metallurgy process.  In the final stages the bushings are impregnated with oil.  These products are also referred to as sintered bushings or by a designation of SAE 841.

Self Lube Bushing
Self Lubricating Graphite Plugged Bronze Bushing

Plug Graphite Bushings – This product is a cast bronze bushing that has been milled and plugged with graphite plugs.  The graphite acts as the lubrication. These are used in applications were the properties of the oil impregnated bushing would not suffice.  Examples of these are high temperature applications or applications with a heavy load bearing requirement.

As you can see these are two completely different product types. From the way they are manufactured to their appropriate uses.  Yet many times they are referred to by the same name.  If you are not sure what product type fits your specific application, contact our sales department via the link below.

Click here to go over your project with one of our sales engineers and they can suggest the best product type for your application. 



February 12, 2013by Michael Russo0

Metric Sleeve Bushing

Often we get requests for bronze sleeve bearings in metric sizes.  There seems to be some confusion on what is standard and what is not.  As well as to the reasoning behind our various stocking programs.

For years cast bronze sleeve bushings have been stocked in standard inch sizes.  These standard sizes were well known throughout the industry.  Various parts were designed to use the industry standards.  There were a number of advantages to this, the main two being lower costs and availability of replacement parts.

As the industry became more and more globally integrated, the need for metric standard size bushings grew.  Just like here in the US, manufacturers overseas developed parts based around the metric system.  As we began using these machines and assemblies from overseas there grew a demand for metric standard bronze bushings to be stocked by US based distributors.  To meet this demand we offer a number of solutions.

We stock metric standard sizes in our oil impregnated bronze bushing line.  This type of product is generally requested by our customers in a short lead time.  Our stocked items usually can be shipped the same day.
Our cast bronze metric sleeves are manufactured by request.  The lead time on this product type is usually 2-3 weeks.  If there is an ongoing need for multiple releases of these standards, we will work out various stocking programs.

For our suspension bushing product line, we stock a full line of metric sizes.  These suspension bushings are manufactured our of cast bronze and are standard parts throughout the Heavy Duty Truck Industry.

As with all of our products, it is best to contact one of our experienced sales engineers.  Describe to them your project and major concerns, and we can work our custom solutions to best benefit you.

Click here to have one of our Sales Engineers develop solutions to your unique needs.

Click here for more information on our cast bronze bushings.

Click here for more information on our oil impregnated bushings.

February 11, 2013by Michael Russo0

From sleeve bushings to wear plates, bronze components can be an integral part in many assembled products.  Rising metal costs and increased global competition have forced many companies to search for new ways to cut costs.  We have summarized our 5 most popular cost cutting strategies that have saved our customers over the past few years.

Download our white paper  “5 Ways to Reduce Your Bronze Component Part Costs” and start saving today.

Reduce Costs of Bronze Bushings, Bearings, and Other Components