Author Archives: Andy Curland

Aluminum Extrusion Manufacturing 101: Understanding Extrusion Die Types

Whether you’re new to aluminum extrusions or a seasoned extrusion designer, it’s important to understand how an extrusion die is designed to create different profile shapes and why those differences impact the die manufacturing cost. While the upfront investment in an aluminum extrusion die may look expensive, shorter lead times and overall lower production costs make it a clear winner for many product applications.

What is an Extrusion Die?

Extrusion dies are essentially thick, circular steel disks containing one or more openings to create the desired profile. They are normally constructed from H-13 die steel and heat-treated to withstand the pressure and heat of hot aluminum as it is pushed through the die.

While it may appear that aluminum is a very soft metal, the reality is it takes a tremendous amount of pressure to push a solid log (billet) of aluminum through a thin, multi-holed die to create the desired shape. In fact, it takes 100,000-125,000 psi of force to push a billet through an 8” inch press.

Aluminum Extrusion Process

To put that force into context, a power washer to clean a car pushes out water at around 2,500 psi. Increasing that pressure to 5,000 psi can destroy the brick on a building. The pressure produced in an extrusion press is 20 times that amount.

Die Profile Categories

While there are a multitude of shapes that can be created using aluminum extrusions, the dies used fall under three categories: solid dies, semi-hollow dies, and hollow dies.

Solid Dies

Solid Profile Extrusion Die Set

Solid Profile Extrusion Die Stack

A solid die creates a final shape that has no enclosed voids/openings, such as a rod, beam or angle. As such, a solid die is typically less expensive to manufacture than other die types.

To produce a solid profile requires a set of parts called a “die stack.” This stack is made up of:

  • Feeder plate controls the metal flow through the die orifice.
  • Die plate forms the shape.
  • Backer plate supports the tongue of die to prevent collapse or distortion.
  • Bolster supports the extrusion load transmitted from the die and backer.

Hollow Dies

Hollow Profile Extrusion Die Stack

Hollow Profile Extrusion Die Stack

A hollow die produces profiles with one or more voids, such as a simple tube with one void or a complex profile with many detailed voids. To produce a hollow shape requires a different die set, which includes:

  • Mandrel is located inside the die and has two or more port holes to generate the internal features of the profile and to control the flow of metal. During extrusion the aluminum billet separates into each port and rejoins in the weld chamber prior to entering the bearing area. The ports are separated by webs, also known as legs, which support the core or mandrel section. Because of these extra components, a hollow die has a higher material and tooling cost, and typically get more expensive the more voids are included.
  • Die Cap is a multi-piece die which makes the shape.
  • Bolster supports the extrusion load transmitted from the die cap and mandrel.

Semi-Hollow Dies

Semi-Hollow Profile Extrusion Die Stack

Semi-Hollow Profile Extrusion Die Stack

A semi-hollow die extrudes a shape that is nearly hollow, partially enclosing a void. Similar to a hollow die, a semi-hollow die set includes a mandrel with port holes, but without cores to make a complete void, as well as a die cap and bolster.

While a solid die may also partially enclose a void, the difference is the ratio of the area of the void to the size of the gap where the tongue is connected to the main body of the die. This ratio is called the tongue ratio. For semi-hollow dies, the tongue ratio is larger than in a solid die, which creates more complexity when manufactured, and in turn more cost.

How Long Do Extrusion Dies Last?

Heat buildup and uneven pressure caused by a profile’s design—use of thin walls, unbalanced shapes, and protruding legs—are the biggest killers to the longevity of an extrusion die. An experienced extruder will design the die to control heat and uneven pressure and slow the extrusion rate to extend the life of a die, but eventually dies must be replaced. Fortunately for designers, most extruders absorb the cost of die replacements.

However, a designer should understand which design decisions will most dramatically impact their upfront tooling costs before sending a design to an aluminum extruder. Changes, where possible, to a profile’s design, tolerance settings, and alloy could save you thousands of dollars in tooling costs.

Learn more about die tooling in our informative whitepaper, 7 Design Decisions that Increase Your Die Tooling Costs.

4 Things to Always Include on Your CAD Profile Drawings

Aluminum Extrusion CAD Drawing

CAD software is an essential tool for today’s industrial designers to explore both form and function of their design ideas. In addition to better visualization of product designs, CAD software is being used to analyze strength and dynamic assemblies helping lower product development costs and greatly shortened the design cycle.

While we still get a few designs on napkins, most designers send us their aluminum extrusion profiles as CAD files. Unfortunately, these drawings sometimes lack important details or have issues that create a lot of back and forth between our manufacturing team and a designer to produce a production quote.

To save yourself time and cost, here are four things to always include in your CAD file when sending an aluminum extrusion profile to your manufacturer.

  1. Make Sure Your Drawings are Readable

Precise measurements are necessary to understand the component’s dimensions and shape and determine the proper container size needed for producing the extrusion die. While CAD drawings are ideal, if your dimensions aren’t readable, can’t be traced to the feature, or the drawing is too cluttered it’s going to create problems.

Do not use too many dimensions on drawings and details. Use only the dimensions that are needed to properly illustrate drawings and details. If two dimension lines show up close together, either put a note on one dimension to clarify what feature it refers to or apply dimensions in a logical flow.

Proper CAD annotation format

Use clear, standard (simple) Geometric Dimensioning and Tolerancing (GDT) call outs with standard Datum call outs. Do not reinvent the GDT handbook. And remember, the more datums you use for fabrication, the more costly the component.

If the shape is complicated, such as requiring compound miter cuts, cutout shape locations in relation to extrusion walls, etc. include the following file types .DXF and/or AutoCAD .DWG / Solid Works .STP file.  Also, indicate “exposed surfaces” on your design drawing so the extruder can give them special attention and protect the finish during both extrusion and post-extrusion handling.

Lastly, verify your drawings show the proper scaling and measurement units English/Imperial or Metric units. Double checking that you start out with the correct scaling and units will save time in the end.

  1. Be Consistent with Your Tolerances

Consistency in tolerancing methods is every bit as important as consistency in dimensioning. As a reminder, tolerance is used to control the amount of variation inherent in all manufactured parts, in particular for mating parts in an assembly. The use of plus/minus (+/-) dimensioning provides the allowable positive and negative variance from the dimension specified.

Most designer use plus/minus (+/-) dimensioning, but some may opt to express dimensional data with double minus or positive tolerances, which is also an acceptable style. Regardless of which style you prefer, it is important you maintain consistency throughout your drawing to make it easier for the extruder to interpret, saving time and reducing errors. Also, use tolerance extrusion dimensions that can be easily checked with calipers and other handheld inspection tools.

Tolerance Settings

If you have custom specific tolerance specifications, and you have a document that calls that out, be certain to supply that document. If it is not sent, your manufacturer will either have to request it from you or have to provide a quote and note that your custom tolerances were not used.

  1. Check Your Tolerance Settings

While standard industry tolerances usually provide adequate precision for most applications (these tolerances are published in the Aluminum Association’s Aluminum Standards and Data Guide), more complex components may call for greater geometric dimensioning and tolerancing in order to achieve the shape-related intricacies of the design. When requested, very precise tolerances of 1/2 or 1/3 of the specified tolerance may be feasible. For example, if the tolerance calls for + or – .010, a tighter tolerance of perhaps + or – .005 could be held, when requested and deemed feasible.

However, to achieve these tighter tolerances may require more involved die corrections, slower extrusion rates, and sometimes a higher rejection rate. All that special care adds up to higher costs. Therefore, carefully consider the application of your part or product when setting tolerances.

A good rule of thumb is NOT TOLERANCE ANYTHING that doesn’t absolutely have to have a tolerance. Aluminum Association standard tolerances will be applied wherever tolerances are not specified. But do ensure you always identify your Critical to Function (CTF) tolerances, such as areas where you are mating hardware.

Pay close attention to the default settings in your CAD programs. Using the default numbers on your drawing program when the decimal setting is three or four places out means every dimension shown appears to require the highest precision.

  1. Calculate Your Tolerance Stack Up

Tolerance Stack UpIf you are designing parts that assemble, also be aware of tolerance stack up. Tolerance stack-up calculations represent the cumulative effect of part tolerance with respect to an assembly requirement. By adding tolerances to find total part tolerance, then comparing that to the available gap or performance limits, you can determine the probability that a part will have a poor or impossible fit with a mating part.

Most CAD software programs include a tolerance analysis tool. Use these tools to automatically check the effects of tolerances on parts and assemblies to ensure the consistent fit of components and to verify tolerancing schemes before sending a profile to your manufacturer. If your program doesn’t include an analysis tool, there are a variety of analysis methods you can choose from and can calculate using a spreadsheet.

Don’t Be Afraid to Ask Your Extrusion Provider for Help

Whether you’re new to aluminum extrusions or a seasoned extrusion designer, your aluminum extrusion manufacturer can help you figure out proper tolerances and stack up, saving you time and frustration. Best-in-class extruders like Vitex work directly with designers to ensure their designs take full advantage of all aluminum extrusion manufacturing functions.

Do you have a project using aluminum extrusion? See how Vitex can save you time and money. Request a no-obligation quote or design review today.

BIA Business Perspective: To NH Lawmakers — Tread Carefully On Energy Legislation

Written by Andrew Curland, Vitex Extrusion CEO & President and incoming BIA Chairman-elect on May 11, 2019

This article originally appeared in New Hampshire Union Leader

Vitex Extrusion is one of many advanced manufacturing businesses in New Hampshire. At our 115,000-square-foot facility in Franklin, we have the capability to produce 30 million pounds of custom aluminum extrusions and components for industries including electronics, building products, automotive and sporting goods.

We manufacture 24/7, meaning we use a lot of power to run our industrial machinery, lights and HVAC equipment. One of the highest operational costs for Vitex is electricity.

This session, the New Hampshire Legislature is pursuing policies that will — alarmingly — add to the cost of electricity and require subsidies from businesses, including Vitex, and residential ratepayers like you. These policies make it difficult for manufacturers, who drive the state’s economy like no other sector, to grow our companies here in New Hampshire.

In fact, expanding in New Hampshire is a growing concern for some of us. New Hampshire individual and business electric ratepayers already absorb energy costs that are 50 to 60 percent higher than the national average — year-round! Still, many bills under serious consideration by legislators this session not only fail to lower electric costs, but instead add to them.

The legislation with the largest potential cost impact for businesses and all ratepayers seeks to increase the state’s minimum percentage obligation for New Hampshire’s Renewable Portfolio Standard, known as RPS. Many states around the nation have adopted RPSes of their own that require a portion of electric utilities’ mix of generation supplied to customers must come from renewable sources such as wind, solar, hydro and thermal.

New Hampshire currently requires that 17 percent of utilities’ energy must come from renewables; that percentage increases to 25 percent by the year 2025. Two proposals this session aim to raise the RPS percentage to 56 percent by 2040. The increase in the 21-year period between 2019 and 2040 called for in this legislation is estimated to add up to $5 billion in electricity costs for New Hampshire ratepayers — businesses, homeowners and renters alike.

With the region already hard-pressed to meet its current electricity demand (grid operator ISO New England predicts a high likelihood of rolling blackouts by the winter of 2024-25 if our regional energy situation remains unchanged), legislators should tread carefully with this legislation. Supporting clean energy and renewables as part of an “all of the above” approach is important in attempting to address high electricity costs. However, there needs to be a healthy balance between the pursuit of clean energy and the need to ensure reliable power at all times, and to do so at rates that are at least stable, if not declining.

In addition to RPS legislation, lawmakers are once again considering subsidizing biomass plants in New Hampshire by requiring utilities to purchase baseload renewable generation at above-market prices. This cost, estimated to be about $25 million annually for three years, would again be passed on to all ratepayers. This language follows a similar bill that was vetoed by Gov. Chris Sununu last year, then overridden by the Legislature.

Although this legislation would seek to protect jobs in the woods products industry, mostly in the North Country, it comes at the expense of energy users, particularly large ones like Vitex, which employ tens of thousands of people throughout the state. It is simply bad public policy for policymakers to choose winners and losers in various sectors of the state’s economy.

Finally, legislators are once again trying to raise the cap on net energy metering from one to five megawatts. Net metering allows consumers who generate excess electricity through their own solar arrays, wind generators or other means, to receive credit for energy sent back to the electric grid. Raising the cap on net metering isn’t the issue — and should, in fact, be aggressively promoted. The issue is the amount of credit those who generate excess electricity are given. The amount of credit in these bills is likely to fall above the “avoided cost,” a figure set by the state’s Public Utilities Commission. The “avoided cost” includes the wholesale cost of power and ancillary services related to generation. Anything paid to net metering customers above the avoided cost means other ratepayers are subsidizing them. That’s simply not fair.

Instead of protecting electricity customers to the greatest extent possible from the high cost of electricity, many policymakers seek to advance policies that will further burden electric ratepayers. If New Hampshire seeks to retain existing businesses like Vitex and enable us to expand, then policymakers should be working to lower electricity costs, not increase them.