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Home / Resources / Aluminum vs. Steel Tooling

Aluminum vs. Steel Tooling

August 31, 2020 by SyBridge Technologies
Aluminum-vs.-Steel

Originally published on fastradius.com on August 31, 2020

Tooling, or machine tooling, refers to the process of building the different types of components and machinery necessary for manufacturing. Tooling can be broken down into two broad categories — soft and hard.

Soft tooling is a cost-effective approach to tooling that’s ideal for low-volume production runs. Many manufacturers use soft tooling for prototyping and creating test units because this process boasts short lead times and fast order turnarounds. Plus, it’s compatible with a wide variety of materials. However, soft tools tend to wear out quickly, so they don’t make sense for higher-volume production.

Hard tooling, on the other hand, is the preferred tooling method for high-volume production runs. Hard tools are more expensive than soft tools, but they’re built to last and pay for themselves over time. The metal they are manufactured from is literally harder, yielding a more robust and resilient mold that can make millions of parts with high precision and accuracy. Aluminum and steel are the most commonly used materials for soft and hard tooling, respectively, and they both bring unique benefits to the injection molding process.

Here are the key differences between aluminum and steel tooling, plus when to use one over the other.

Why Material Choice Matters

For engineers and product teams, choosing the right material for their tools is just as important as choosing the right material for the overall project. A well-made tool made from the right material makes for a smooth manufacturing process.

Engineers should consider production size and production speed first because these factors are key considerations in determining appropriate tooling materials. After that, engineers can begin to think about specific qualities they want in their tool, such as wear resistance or the ability to accommodate complex designs. Once material options have been whittled down, engineers should choose the material that satisfies the maximum number of criteria for the lowest possible cost.

The Case for Steel Tooling

When it comes to durability, steel tooling outpaces aluminum tooling by a wide margin. Steel offers superior strength and is able to withstand years of repeated use, making it the best choice for high-volume production runs. A well-designed, well-maintained steel tool can produce millions of parts without breaking down. As such, cost-per-part decreases as quantity increases.

Steel’s strength also allows designers to explore a wider range of applications and get creative. When a part requires complex, extremely small or precise features — features like non-uniform walls or narrow mold cavities that would normally push the boundaries of injection mold design best practices — steel molds yield better results. This material is better able to retain its shape in the presence of complex geometries.

Steel offers superior strength and is able to withstand years of repeated use, making it the best choice for high-volume production runs.

Also, steel can be used with advanced resins that are reinforced with glass, fiber, or other additives. Softer metals like aluminum are more susceptible to scratches and erosion from the additives, which can negatively affect the tool’s surface finish.

The most significant drawback to steel tooling is cost — steel molds generally require high upfront costs. Also, steel molds take up to seven times longer to heat and cool than aluminum molds, which extends cycle times.

The Case for Aluminum Tooling

Steel is durable, but aluminum offers other valuable advantages. Aluminum tooling is more cost-effective than steel tooling for many reasons. First of all, initial investment costs are lower — aluminum molds typically cost around $1,500 — and engineers will get better value for low-volume production runs. Also, since this material is ideal for simple mold designs, engineers can also save on manufacturing time and costs. In 15 days or less, engineers can build the aluminum mold and complete their production run.

Aluminum tooling also gives engineers more options than steel when it comes to manufacturing. Steel molds are notoriously difficult to modify or repair because the material is so strong, and, for bigger design changes, engineers often have to start over with an entirely new mold if production errors have occurred. Aluminum is softer and easier to repair, plus its superior heat dissipation reduces the number of parts rejected due to shrink, warp, and sink marks.

Steel is durable, but aluminum offers other valuable advantages, including being more cost-effective and versatile.

Aluminum tooling does have its limitations, however. Aluminum isn’t as durable as steel and molds tend to wear out after a few thousand production cycles. This can cause nonconformities in the part that must be retooled, which drives up costs. Another point to note is that, when tooling with aluminum, texture selection is fairly limited due to the material’s low density.

Tackle Tooling With SyBridge

Engineers should consider steel tooling if they need to manufacture at least 50,000 highly detailed parts and have the funds to invest in expensive molds that they’ll use for the foreseeable future. Aluminum tooling is worth considering for low-volume production and for those looking for a quicker, more cost-effective alternative to steel. As always, product teams should spend some time researching tooling materials to ensure they’re making the best decision for their project.

An experienced manufacturing partner like SyBridge can help engineers and product teams weigh their options and choose the best tooling method for their production run. Our team of expert technologists, engineers, and designers are prepared to streamline the product development process — from ideation and prototyping to post-production and fulfillment, faster than you thought possible. Contact us today for a quote.

Category: Knowledge CenterTag: Injection Molding, Materials

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Polyoxymethylene (POM), more commonly known as acetal or its branded name Delrin®, is an engineering plastic offering low friction, high stiffness, and excellent dimensional stability. Polyoxymethylene is a category of thermoplastics and includes many different formulations of the material, all of which vary slightly. As such, it’s important to learn as much as you can about each type before choosing one for your next project. Delrin® is a semi-crystalline engineering-grade thermoplastic widely used to create highly precise parts. In general, Delrin® provides impressive dimensional stability and sliding properties. It’s known for its high strength, wide operating temperature range (-40°C to 120°C), and excellent mechanical properties. Here’s everything you need to know about this material, from how it’s made to its best-fit applications. Inside the polyoxymethylene production process Acetal was first discovered by German chemist Hermann Staudinger in 1920 before it was commercially synthesized by research chemists at DuPont, the original manufacturers of Delrin® plastic, in 1956. Like all other plastics, acetal is created by distilling hydrocarbon fuels down into lighter groups called “fractions,” which can then be combined with other catalysts via polymerization or polycondensation to produce a finished plastic. To make an acetal homopolymer like Delrin®, anhydrous formaldehyde must be generated by causing a reaction between aqueous formaldehyde and alcohol to form a hemiformal. The hemiformal is then heated to release the formaldehyde, and the formaldehyde is polymerized by anionic catalysis. The resulting polymer is stabilized when it reacts with acetic anhydride, which creates polyoxymethylene homopolymer. Acetal comes in many different commercial varieties and formulations, each with its own advantages and disadvantages. For example, Delrin® 500 is medium-viscosity, all-purpose polyoxymethylene that has a good balance of flow and physical properties. It can be used to produce parts via CNC machining and injection molding and is frequently used to manufacture mechanical parts, fuel systems, and fasteners. Delrin® 1700P, on the other hand, is a very low- viscosity, fast-molding resin that is best suited for parts with complex shapes, thin walls, long flow paths, or multi-cavity tools. It also offers the best molding thermal stability for deposit-free molding in demanding conditions. Since there are dozens of different formulations of acetal, it’s important to do your research and make sure your prospective plastic offers all of the properties you need for your application. Delrin® plastic properties and mechanical specifications small black Delrin pieces Delrin® can also be found in all-purpose industrial equipment like bearings, gears, pumps, and meters. Acetal’s excellent mechanical properties make it extremely versatile, offering a unique blend of properties that you won’t find in most metals or other plastics. Delrin® plastic is strong, rigid, and resistant to impact, creep, abrasion, friction, and fatigue. It’s also well known for its excellent dimensional stability during high-precision machining. Acetal can also stand up to moisture, gasoline, solvents, and a wide range of other neutral chemicals at room temperature. From a design standpoint, parts made with extruded POM naturally have a glossy surface finish. Since acetal is compatible with CNC machining, injection molding, extrusion, compression molding, rotational casting, and more, product teams are free to choose the manufacturing process that works best for their budget and their needs. However, it’s worth noting that Delrin® plastic is typically very challenging to bond. Acetal material properties vary by formulation, but the mechanical properties for Delrin® 100 NC010, one of the most popular formulations, include: Tensile modulus: 2900 MPa Yield stress: 71 MPa Yield strain: 26% Density: 1420 kg/m3 Charpy notched impact strength, +23°C: 15 kJ/m2 Coefficient of linear thermal expansion, normal: 110 E-6/K Water absorption: 0.9% Delrin® does have a few limitations. For instance, even though Delrin® is resistant to many chemicals and solvents, it’s not very resistant to strong acids, oxidizing agents, or UV radiation. Prolonged exposure to radiation can warp the color and cause the part to lose its strength. Also, this material isn’t readily available in a flame-retardant grade, which limits its utility for certain high-temperature applications. Why choose Delrin® plastic? These limitations notwithstanding, there are many reasons to choose acetal over other materials. When compared to other plastics, acetal offers better creep, impact, and chemical resistance, better dimensional stability, and higher strength. It also has a lower coefficient of friction. Acetal outpaces certain metals as well. Parts built with this material have a higher strength-to-weight ratio, better corrosion resistance, and offer more opportunities for part consolidation. You can build thinner and lighter parts faster and at a lower price point with acetal than with a comparable metal. Delrin® plastic can be found in almost every major manufacturing sector. In the automotive industry, common applications include heavy load-bearing gears, fuel system components, loudspeaker grilles, and safety system components like seatbelt hardware. Delrin® can also be found in all-purpose industrial equipment like bearings, gears, pumps, and meters. In the consumer goods and appliances space, this material can be used to make anything from zippers and pens to knife handles and lawn sprinklers. Getting started with Delrin® There’s a lot for product teams to love about Delrin®. It’s strong, stable, versatile, and its excellent mechanical properties make it a good choice for a wide variety of applications in a number of industries. However, with dozens of different formulations of acetal on the market, it can be very challenging to determine which one might be the best fit for your unique project. A seasoned manufacturing partner can help demystify the material selection process. When you partner with Fast Radius, you partner with a team of on-demand manufacturing experts who have years of experience helping product teams navigate material selection. We’re well-versed in the wide range of materials that can be used for both traditional and additive manufacturing — including Delrin®. Once you’ve selected the Delrin® formulation that’s the right fit for your application, our team of experts can help facilitate the entire manufacturing process — from design and prototyping to production and fulfillment. With a full suite of manufacturing services including CNC machining and injection molding, Fast Radius can bring your vision to life quickly and easily. Contact us today to get started.

Know Your Materials: Delrin (Polyoxymethylene)

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