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The Mac Metals Manufacturing Process

The Mac Metals Manufacturing Process

Many customers ask our team at Mac Metals, “What Goes into your Manufacturing Process,” and “What Makes Your Process Better than Competitors?” Well, aside from being the only 100% American-Made provider of custom extrusions, Mac Metals has a specific process that allows us to provide high quality extrusions on time and above standards.  Learn what else goes into the Mac Metals manufacturing process by reading more.

Raw Materials

Architectural Brass, bronze and nickel silver are copper alloys that benefit from a well-developed recycling infrastructure and an economic value that drives recovery, recycling and reuse. Raw material charges are made up of scrap purchases, process scrap and virgin metal. Over 90% of Mac Metals casting charges come from recycled materials. Incoming melt stock is chemically tested upon receipt. Clips, stampings, rod-ends, pipe, tube, borings, shear stock and other forms are pre-weighed and staged for each casting heat.

Related: Choosing the Right Alloys

Casting Process

Pre-weighed scrap is charged into a 10,000 pound capacity, 200KW channel-type Ajax Magnathermic induction furnace. Heats are skimmed and poured into 15 vertical cast molds to form 5½” diameter billets in logs 54” long. Samples of molten metals are taken from the furnace before each pour.

Each heat is assigned an individual identification number providing traceability throughout the manufacturing process.

Billet Preparation

Logs are cooled and molds stripped. Each log has an attached identification tag with heat information.  Logs are staged on a billet saw and billets are cut to the optimum length for each custom extrusion order. Billet length is determined by extrusion ratio and customer requirements.

Billet Heating

Billets are loaded into a 600 KW high-frequency induction heater and brought up to extrusion temperature (1350 to 1500F, depending on alloy and extrusion ratio) and called for use at optimum temperature.

Die and Tooling Heating

Dies are heated for a minimum of 6 hours at 400 to 800F. Dummy blocks and other tooling is also heated before use.

Extrusion Process

Billets are loaded into the container of the 900-ton Gantz direct extrusion press. Headman orients billet direction, loads dummy block and lubricates extrusion die. Container is sealed and ram upsets billet and extrudant is pushed through the extrusion die in a semi-plastic state requiring up to 5000 PSI and travel at 300” per minute. The remaining 1 to 2” of the billet remains in the container, the product end is cut and butt removed. Product advanced by puller or by hand.

Related: Extruded Bronze Curtain Wall in Seagram Building


Extrudant is advanced on a graphite table. Cable puller pre-straightens. Run-out men pull and hot-work (hand straighten, open key end dimensions and test hot surface for die lines and cracks) to minimize down line stretching and straightening requirements. Extrudant is loaded onto walking beam for cooling. Water spray added to larger items.


Cooled extrudant is stretch-straightened in one of three stretcher machines with 15, 25 and 50 ton capacities.  Long, light-weight lengths are stretched at the run-out table. Heavier lengths are pre-cut and transferred to one of two off-line stretchers. The process of stretching increases the length of the extrudant by one to three percent achieving longitudinal straightness, removing bow and correcting dimensional tolerances. Grippers are selected to eliminate distortion.

Related: Beginner Tips for Fabricating and Coating

Process Lengths

Stretching creates gripper marks and distortions that are cut off before additional stretching, or roll straightening is required. Extrudants made in multiple lengths may be cut to size at this time.

Related: Nickel Silver Compared to Stainless Steel

Roll Straightening

Mac Metals is unique in the industry by utilizing roll forming to further correct for straightness, flatness and dimensional requirements. Modified horizontal roll formers in single, or double shaft configuration provide straightness and flatness requirements that exceed standard mill tolerances. Mac recently added a Siefer “Profile Correction” machine for heavy weight extrusions.

Finish Cutting

Three cold saws are used to cut material to the final customer required length. Typical customer lengths range from 10 to 20’ with 16” being the standard for architectural shapes.

Related: Finishes for Brass, Bronze, and Nickel Silver

Additional Fabrication

Mac Metals offers precision cutting (tight tolerances), slug-cutting (near-net parts), and sanding, drilling, tapping, milling and other value-added services after the extrusion process.

Related: Welding Bronze Extrusions


Mac Metals maintains a box shop to provide custom boxes for each product shipped. Boxes are designed to consider weight, nesting and length of the product. All boxes have six sides and are nailed and banded for strength. All boxes have cleats for handling.


All product is quoted FOB, Kearny, NJ.  For a deeper look into the Mac Metals Pricing, read our recent blog on Pricing and Metals Volatility.


Mac Metals offers a wide variety of extruded shapes employing state-of-the-art CAD/CAM and Wire EDM systems in a fully equipped machine shop. Our tooling experts work with our customers to make their designs most efficient for the extrusion process. This collaboration early in the design process ensures a cost-effective product and may improve working tolerances. Tooling costs for extrusions are comparatively inexpensive when compared to forgings, castings, roll-forming and other competitive materials processes. All dies, special rolls and tooling purchased by the customer for custom extrusions shall remain in the control of Mac Metals and used and maintained exclusively for the customer.


All Mac Metals product is manufactured to an M30 Hot Extruded Temper.

Learn More about Mac Metals

Mac Metals is a provider of custom extrusions to architects and construction companies.  Located in Kearny, New Jersey, we support architectural projects across the nation.  Take a second to look through our gallery, read more about our capabilities, and reach out to us for more information.