Depending on which copper alloy you chose, you can achieve the strength of steel, superior corrosion resistance and/or durability in applications that require wear and galling resistance. But first, let’s differentiate between brass and bronze, because in some quarters of industry, the terms are used interchangeably.
Aluminum Bronzes are a family of copper-based alloys that use iron and nickel in their chemistry - but rely on aluminum as the principle alloying element. Aluminum significantly adds to the strength to the point that it is similar to that of medium carbon steel. The additional advantage is that aluminum bronze also possesses excellent corrosion resistance. It is that strength and corrosion resistance that gave rise to the early use of aluminum bronze.
A small adjustment in metallurgy causes significant changes in performance. This recognition of other properties has led to the use of Aluminum Bronzes for a variety of parts requiring strength, hardness, resistance to wear and galling, low magnetic permeability, resistance to cavitation, erosion, softening and oxidation at elevated temperatures. These properties, together with ease of weldability, have greatly extended the fields of application for Aluminum Bronze.
The days when manufacturers had a host of technical experts on staff are past in many industries. And this at a time when material choices are broader and product performance demands are higher than they have ever been. So the situation will not get any easier. Here are just four real life examples where MetalTek International helped a customer's heat, wear, or corrosion problem.
If you have a question about alloy selection, if you manufacture products that operate in harsh corrosive, high wear, or extreme temperature environments, or if you are simply looking to improve product performance, contact MetalTek.
#1.) Bearium Solves Load and Friction Problems in Mobile Crawler
From the days of Apollo program through the Space Shuttle a heavy duty crawler has carried the enormous weight of space vehicles down the one-mile path to the launch pad. Early designs used to carry this load were subject to sudden catastrophic failures of the roller bearings, jeopardizing timing of the launches. The crawler went through an emergency redesign to replace the roller bearings with sleeve bearings manufactured using Bearium B-10, a high-lead bronze that is only available from MetalTek International. Designs using Bearium delivered acceptable performance in an application that would then feature much higher friction. Bearium is used in the space craft crawler application to this day.
#2.) Creating a “Memorial to Last a Lifetime”
Working with architects to create a “Memorial to Last a Lifetime” is no small task. Every step of program management is critical—from materials and engineering, to budget compliance, to execution. Initially, the Pentagon Memorial team approached MetalTek International about choosing the “right” alloy to last 150 years; as various materials were trialed and budgeted, the ultimate selection came down to a restricted-range 316LN (CF3MN-Mod) alloy that would meet the design requirements and still be producible to tolerances such that 184 Memorial Units, each weighing over half a ton and measuring over 12’ (4m) in length, would seem to be “identical.” Specialized tooling, processing and fixtures were developed, trialed, and modified against an aggressive timeline. In the end, MetalTek met the Vision, the Budget, and the Schedule.
Partnering with a supplier that brings a full range of metalworking processes lets you be confident that you are getting the best metalworking advice – and not just being sold on an idea because it is the only answer a supplier has. The replacement of multi-piece weldments or highly-machined hogouts by single piece castings has been proven time and again to be one of the most effective ways to reduce real product cost. Here are just five real-life examples of when the casting process was a better choice for the customer than a fabrication or forging.
#1.) Centrifugal Casting Replaced Complex Fabrication
Controllable pitch propulsion (CPP) systems provide the ability to alter the angle of the ship’s propeller while in use, allowing for different performance during cruising and maneuvering. A centrifugal hub provides the strength and size needed to transfer up to 50,000 shaft horsepower to five attached propeller blades. The hub and 15 other accessories that MetalTek produces for the CPP must perform in corrosive environments for the life of the vessel. Fabrications previously used were very intricate, with multiple pieces and welds, and much machining. The single piece nickel aluminum bronze hub that MetalTek has supplied for 35 years is the largest, most complex centrifugal casting ever produced. The use of a single piece part in this application eliminates welded joints and defects in those fabrications that are only discovered after finished machining.
#2.) Fabrication Could Not Achieve Dimensional Stability
International research, including that done in conjunction with the DOE, strives to create conditions in the lab necessary to support nuclear fusion. Huge machinery, such as the “Z-Machine”, can create temperatures of 2.9 million °F (1.6 million °C) for fractions of a second. Integral components must have the ability to conduct electricity and perform in the machine’s water cooling system. Attempts to use fabrications in those applications were abandoned because dimensional stability could not be achieved. The customer came to MetalTek for a casting solution, a particularly challenging one because of the product’s large size. MetalTek specializes in large investment castings, and now supplies products with better dimensional consistency than was available with a fabrication.
The continuous casting process involves pouring molten metal through a die of the desired outside profile. If shaping on the I.D. is also desired, the material may flow around a mandrel to create that profile. As a result, continuous cast product is often chosen to dramatically reduce machining cost. Here are just two examples of when the continuous casting process resulted in a cost savings.
AMS 4880 Alloy for High Wear Bushings and Sleeves
Taking off in an airplane is exciting but safely landing at your destination is the ultimate goal of flight. The landing gear is just one of the many important systems MetalTek’s aerospace customers design and build for commercial use. Two major landing gear components are bushings and sleeves that need to withstand wear from airplanes transitioning from 140-190 MPH to taxi speeds in a matter of seconds. MetalTek’s onsite metallurgical group recommended changes to their customer’s specifications to use continuously cast components made of AMS 4880, a nickel aluminum bronze (NAB) alloy, which met the component’s wear demands and offered an attractive cost savings over forged material.