Published 5/1/2005

Improve Shop Efficiencies with The Right Material Supplier

What to look for when choosing a single source for your product needs.

Joe Harms

Products

Let's first address why moldmakers should choose an aluminum cast plate supplier over the alternative choices of wrought aluminum plate or steel. Listed below are just a few key reasons why cast plate is quickly becoming the material of choice in an array of moldmaking applications.

• Stress Free
As opposed to rolled plate, cast plate requires no stress relieving, resulting in better dimensional stability during machining. How is this possible? A cast product undergoes no internal cold-working during its production, eliminating the need for stress relieving. In contrast, the rolling operation during wrought plate production induces mechanical stresses into the plate that may not be completely removed during subsequent thermal treatment.

• Critical Tolerance
Cast plate maintains critical dimensional tolerances, resulting in a mold that is able to provide the very tight dimensional control needed in the production of plastic and rubber parts. This is advantageous when compared to aluminum rolled plate, which often exhibits internal stress and can distort after machining.

• Productivity
Cast plate improves productivity thanks to a faster cool down rate than tool steel. Aluminum's thermal conductivity is several times that of steel, resulting in shorter cooling cycles and a more uniform thermal profile throughout the mold during part manufacturing.

• Ease in Handling and Machining
Because it's one-third lighter than steel, aluminum cast plate allows for safer and easier handling when working with large molds. In addition, aluminum is machined at much higher rates than steel, which results in significantly faster mold production.

Chart 1

Product	Mold Plate		Tool and Jig Plate
Recommended Alloy	2xxx	5xxx	7xxx	5xxx
Features	• Excellent Machinability • Specified in Various Mold Applications • Weldable • UT Inspected	• Low Density • Improved Scrap Recovery • High Strength • Excellent Weldability • UT Inspected	• Industry Standard • Applications Requiring Superior Dimensional Stability •Specified in Tight Tolerance Applications	• Superior Anodizability • Excellent Weldability • High Strength • Low Density • Improved Scrap Recovery
Gauge Range Availability	>2"-30"	>4"-27"	0.25"-2.00"	0.375"-4.00"
Width Range Availability	64" Width	74" Width	72.5" Width	72.5" Width
Surface Finish (recommended)	• Machined Both Sides (<25 RMS) • Sawed Surface	• Machined Both Sides (<25 RMS) • Sawed Surface	Machined Both Sides (<20 RMS)	Machined Both Sides (<20 RMS)

Chart courtesy of Pechiney Cast Plate.

Capabilities

Now that we know what type of supplier to look for, what capabilities should you look for when choosing one? When it comes to working with a supplier, your selection should begin and end with one question: Do they offer a complete line of products for all of your common—and not so common—needs?

Moldmakers need an aluminum cast plate that provides machinability, dimensional stability and consistent mechanical properties throughout the thickness of the plate. These factors are critical in applications such as low-pressure injection molds, large blow molds for the automotive industry, rubber molds and structural foam molds. But when looking for a supplier that offers a product with these properties, be sure to choose one that also offers a lower density version. This financial advantage decreases cost and increases scrap recovery. An example of this is the 5083 alloy, which has four to five percent lower density than other 2xxx and 7xxx alloys commonly used in mold applications. And, because of its popularity in a wide array of applications, the 5xxx alloy nets a premium price on the scrap market (see Chart 1).

The Essentials

It's easy to see why breadth of product line is so important. After all, you are looking for a single source for your product needs. However, there are some additional items to consider when choosing your supplier.

• Look Beyond Steel
The strength to weight advantage doesn't have to end with steel versus aluminum comparisons. Be sure to choose a supplier that offers a 5 percent weight savings when compared to other aluminum alloys routinely used in mold plate applications.

• Consistency
Make sure your supplier offers a cast plate product with consistent mechanical properties throughout the entire plate regardless of thickness. This makes it more machinable than wrought plate alternatives.

• Ultrasonically Inspected
Choose a prospective supplier that guarantees ultrasonically inspected material, ensuring that its products are free of voids and inclusions. You'll be glad you did; the result is excellent machinability through the thickness of the plate.

• Weldability
The superior weldability improves ease of use when mold alteration or repair is required.

• Choice of Surface Finish: Machined or Sawed
Choosing a supplier that offers a machined surface eliminates the need for additional milling or surface grinding—and the need for one more operation. To minimize costs (for those instances where cost-savings are paramount), a precision sawed-finish is an option.

• 5xxx Alloy
Select a supplier whose products feature high-strength, corrosion resistance and excellent anodize response and weldability. In addition, 5xxx alloys command a premium in the scrap market when compared to 2xxx and 7xxx alloys.

A complete product line, high strength to weight ratio, excellent machinability, consistent anodize response and weldability should all be at the top of your list when considering who to choose as your one source supplier. But beyond these, a supplier's ability to listen may be the most important trait. By listening to its customers, a supplier will be able to provide answers to questions that haven't been asked yet and develop products that meet needs not yet known. The range of applications will continue to expand, so be sure you work with a supplier that can do the same.