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Category Archives: Die Casting Surface Finish

Design for Manufacturing – Die Casting

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design-for-manufacturing-die-casting-partimage1There are several processes which can be used to efficiently manufacture parts.  When a project engineer has a solid idea of how the parts all come together to make the end product, it is time to consider which manufacturing process will be the optimal solution for the individual components.  Die casting is one of many processes that should be considered.

Is Die Casting Right for My Part?

To learn more about if die casting is the appropriate process for your project, DOWNLOAD TO VIEW THIS WEBINAR.  You can also contact the CWM Engineering Team for any questions you may have at sales@cwmtl.com or 630-595-4424.

Application Review

When considering DFM for a die casting, even the smallest details may affect cost and performance.  It is imperative for the die cast engineering team to understand the application of the end product and what the part function will be.  The following factors are considered in the initial review:

  • Mating Part review – what does this connect with? Is it an assembly?
  • Environment – what are the features and functions of the part?
  • Product testing – Are there any additional tests the part needs to undergo? What other tests will the product need to undergo that pertain to the die casting?
  • Are there any cosmetic or finish requirements? (Click Surface Finishes for Die Castings or Guide to Surface Finishing for more information on finishes)

Preliminary DFM meetings It is important to remember that working with the die caster and providing as much as detail as possible in preliminary meetings will determine whether or not die casting is the correct process for the application.  Selecting a die cast supplier with in-house capabilities for post-casting operations (i.e. filing, deburring, CNC, machining, coating, assembly, etc.) will make the process much easier and keep the project running as smoothly as possible.   It is vital to find a die caster that is transparent in all their communications and non-biased.   Reputable die casters would never recommend the die casting process; a specific alloy; or a design that is not going to be an effective solution.

Web-based meetings or face-to-face meetings can be either on-site at a die caster or arranging a die caster to visit a desired location.  A visit to the die caster will open the opportunity for both the die casting team and the in-house team to develop a partnership, review best practices, and get an idea of what technology they currently use and what their plans are for the future.

Hosting an in-house company seminar (where the die caster visits) will allow the program to be tailored to the needs of a company and allow the die caster to review numerous in-house samples.

Whichever option is selected – it gives each team the ability to capitalize on strengths and get a feel for the feasibility of a project when considering die casting.

4 Major Factors in Part Design to Consider for Die Casting

In the preliminary stages of moving from concept to ready-to-tool design, a product engineer engages in exploring manufacturing solutions would be best for the part.

In order to get an idea of what to consider in DFM for die casting, here are 4 factors that are important to consider:A die cast part and wall thicknesses.

  • Uniform Wall Thickness

Uniform wall thickness aids filling, improves quality, and lowers cost.  Heavy mass areas should be avoided.  Ribs should be utilized where increased strength or stiffness is needed.

  • Design/Cost Trade-Offs

“As-cast” parts provide a consistent geometry, but sometimes machining is needed (to hold tighter tolerances).   Similarly, more complex tooling can be used instead of machining, but in addition to increasing tooling costs, it may result in stepped parting lines and higher costs to remove flash.  There is also the possibility to having several mating parts consolidated into a single casting resulting in substantial piece cost savings.  Cosmetic or performance requirements, are cost drivers and can involve added polishing, coating, or corrosion protection strategies.   These are just a few of the cost tradeoffs to be considered.mold flow analysis of a die casting helps teams determine where design changes can (or can't) be made.

  • Mold Flow Analysis

Running a mold flow analysis can give engineers on both sides a look at optimizing for part geometry and filling.  It solves several of the major issues upfront so a re-design can be worked in prior to creating the tool and going into production.  This ultimately will translate into both time and cost savings.

  • Drawing Development

It is generally suggested that notes from a previous process are to be excluded from updated drawings.  The notes should be specific to what is required in the die casting process.

additional details on the CAD drawings will determine if the part is suitable for a die casting.Datum schemes and tolerances are very important and can influence whether the part can be made as-cast, or if it will require machining?    Notes can help guide interpretation of the drawing, but it is best to work with a die caster who can help to align the notes to the manufacturing process best suited to your application.   The use of industry standard terms and specification guidelines is strongly recommended.

A good die caster will know whether the part can be made with the die casting process.   A great die caster will have enough know-how to direct an individual towards another process if die casting is not a good fit, or help you to optimize the design if die casting is a good fit.   Contact our team today for more information on how die casting can benefit your project.  E-mail sales@cwmtl.com or call 630-595-4424.

The Verdict Is In… CWM and Stenograph Win the IMA Award for Die Cast Design!

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Stenograph Luminex parts were cast by Chicago White Metal. Screen frame and Keyboard Chassis

The Screen Frame casting (left) and the Keyboard Chassis casting (right) are the 2016 Winners for the IMA Award for Design Excellence.  

IMA Die Casting Excellence Award for Magnesium Part

The IMA Award makes its way home from Italy to CWM!

The verdict is in – Chicago White Metal joined forces with Stenograph to not only meet the requirements for producing the high-end stenotype machine parts, but also to win the “case” for Commercial Castings – Excellence in Design from the International Magnesium Association (IMA).

The International Magnesium Association (IMA) was founded in 1943 with a mission in mind – “promote the use of the metal magnesium in material selection and encourage innovative applications of the versatile metal.”

Stenograph produces high-end, portable stenotype machines for court reporters with exceptional quality.  The Stenograph Luminex is more than 1 lb. lighter than the previous model, 33% thinner, and stands at a mere 2.5″ tall.

Walter & Carolyn Treiber accept the prestigious IMA award for die cast design excellence for magnesium, for customer Stenograph

Walter & Carolyn Treiber accept IMA Award for Die Cast Design.

This Award of Excellence is an annual award that is given to the company demonstrating an outstanding example of the use of magnesium.  The magnesium screen frame serves as an ideal metal replacement for plastic, creating a high-end “feel” and look to the end product.  The keyboard chassis replaced aluminum with magnesium for decreased mass, allowing the final product to offer maximum portability.

Walter Treiber explains at the IMA’s World Conference in Italy why magnesium was ultimately chosen for the die cast design of this particular casting.

CWM Ice Sculpture at 2016 IMA World Conference in Italy

The International Magnesium Association (IMA) Creates a CWM Ice Sculpture at the IMA World Conference Closing Banquet in Italy.

Magnesium’s ability to be die cast with an excellent surface finish allows the screen frame part to readily accept a highly cosmetic appearance, giving a sleek, reflective surface finish to the screen frame.  A court reporter is expected to type the official transcripts of court hearings several times a day with amazing efficiency, so the decision to cast the keyboard chassis in magnesium reduced the overall end product mass, which increased portability from one courtroom to the next.”

Congratulations to Chicago White Metal and Stenograph for the success and excellence in die casting!

Visit Stenograph for more information on the Stenograph Luminex.

Start with the Die Cast Finish

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die casting starts with the surface finish

One of CWM’s Sales Engineers coined the phrase, ‘Start with the finish in mind.’   This is because the specific design features of a die cast part, in almost every case, has a direct impact on achieving the required surface finish specifications. For this reason, all die casting finishing requirements should be discussed with the die caster early in the design phase.

Die castings and subsequent surface finishes have a symbiotic relationship. That is, the results of each process “work together,” and each benefit from the relationship. For example, aluminum die castings that call for a cosmetic surface will require attention to the location of the casting’s parting line, gate, overflows and vents. If these design features interfere with or blemish any of the part’s designated cosmetic surfaces, undesired results will occur.

The importance of reviewing the finish with the die caster early in the project is also exemplified by the tool design. Cosmetic surface requirements for the custom die casting may require special finishing of the cavities of the die. In addition, the cover die half will generally be used to produce a specified cosmetic surface. This permits the ejector die half to contain the required ejector pins— which assist in ejecting the part cleanly from the die.

It is essential that the die caster understands how parts mate with other components in the final product assembly. The die caster will analyze the design to assure a quality finish, and equally important, to make sure that tolerance specifications will be met. If this step is omitted, it could lead to additional finishing processes that increase piece price costs.

Cost is certainly another driver to have an early discussion with the potential die cast supplier. As discussed earlier, the geometry of the design’s features have a direct impact on the final surface finish. An early review with the die caster can result in minor modifications (i.e., critical surfaces, edges, and mounting features) that reduce the need for surface preparation before the final coating. The end result is increased efficiency which has a direct impact on lowering the final production cost.

Unlike many die casters that only produce raw castings, CWM is a full-service, die cast-to-finish supplier. Over 90% of our castings include additional post-cast finishing operations prior to shipment to our customers. With that high volume of post-finishing experience, coupled with over 75 years of performance, our die cast finishing expertise is unsurpassed. Further, when it comes to recommending the right alloy with the optimal finishing process, CWM is in a unique position to provide unbiased information since we work with the most widely used metals: aluminum, magnesium and zinc. If you would like to tap in to that experience by reviewing your project with a CWM Sales Engineer, please call us at 630-595-4424.

Additional Die Cast Finishing Resources

Aluminum Magnesium Zinc Die Casting Design Assistance

Die Casting Design Center is a valuable free resource to aid you when designing for die casting products. You’ll get access to an educational hub—the largest collection of technical die casting content in the industry—geared to assist OEM design engineers, purchasing specifiers, and OEM design consultants through the die casting process.

All these die cast finishing resources are available for a free download in DC2:

die casting surface finishes quick guideCWM’s Quick Guide to Surface Finishing for Die Castings:
A comprehensive 8-page condensed resource on evaluating surface finishing alternatives and optimizing component finishing decisions for magnesium, aluminum, and zinc die cast products. Contains illustrated die cast surface design guidelines for enhancing finishing results; Describes how part design features can impact your final finishing results; Features a comparison table rating 33 surface coatings on relative cost, appearance, wear and corrosion resistance; Presents recommended finishing steps and optimum coatings and finishes for a range of typical die cast housings and components, from strictly functional components to highly-cosmetic parts and those with fail-safe EMI-RFI shielding requirements.

Die Casting Surface Finish Webinar thumbnailSurface Finishes for Die Castings – pre-recorded webinar:
This Webinar provides practical knowledge of the different types of surface finishes for die cast parts; the factors to consider when selecting a die cast surface finish; the advantages and limitations of common finishes recommended for die cast components; and important finishing considerations to build in during the die cast design phase.

CArticle on Corrosion-Resistant Trivalent Chromate surface finish for die castingorrosion-Resistant RoHS* Compliant Trivalent Chromate Coating:
Latest information on Trivalent chromium, which is now a proven alternative to hexavalent chromium coatings and meets new U.S. and European Union environmental mandates for die cast products. Economical, with a cosmetically pleasing surface finish, it offers high corrosion resistance for CWM aluminum, zinc, and magnesium die castings.

NADCA Die Cast Finishing Checklist thumbnailNADCA’s Finishing Checklist:
Provides a convenient method for assuring that important factors involved in the surface finishing of cast parts are evaluated and clearly communicated between the purchaser and the caster.


High Pressure Die Cast Coupons:
When making a decision between different surface finishes for your product, seeing the actual finish on the metal can be a valuable aid to the decision process. CWM offers coupons in three different alloys (aluminum, magnesium, and zinc) with a variety of options for die cast finishing.

Key Questions to Ask When Sourcing the Best Die Caster for Your Project

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After months of research, deFindDCveloping a die casting design concept and validating it, you’re ready to move into the next phase of the project:  selecting a die caster to turn the concept into a reality.  Unless you have an existing relationship with a reputable die casting supplier that you’ve established, finding the best metal die caster to produce your product can be an arduous task.

There are some key areas that should be considered when choosing a die caster, whether it is for aluminum, magnesium, or zinc materials.   Certainly, the cost of die cast tooling and production will carry much weight in the decision process, but a good die caster will offer much more than a competitive price.  And, if you’re just comparing on price alone, be aware that some additional services may be included in the cost to build the tool.  In such cases, one quote for metal die casting may be higher than another so that you may not be comparing apples to apples.  Be sure to have a full understanding of what is included in the quote.  Also, a quote with additional services may cost more upfront but it can literally save you thousands of dollars over the life of your product. That’s why it’s important to consider several areas when selecting a good metal die caster and understand what’s included in the quote.

Before building an expensive tool for your metal die casting design, be sure to request a comprehensive description of the engineering consultations that will be held with your team.  The die casting engineers should fully understand your concept and its performance requirements in the end product.  With that understanding, the engineers can optimize your drawing for maximum performance in both the die casting process and its function in the end product.  The die casting engineer’s preplanning and analysis can recommend cost saving measures —or prevent costly mistakes over the project life.

With the initial engineering consultation, does the die casting supplier have the ability to take advantage of advanced technology using process simulation software (e.g., Magmasoft®) before the tool is built? Using your CAD file, they can use the software to predict and optimize metal flow, air entrapment, metal velocity, thermal balance, hotspots etc., during the die casting process.  This will assure a quality die casting design, shorten lead times and can lower production costs.

Can you trust that you’re getting an unbiased opinion about the correct metal alloy to use for your project?  There are multiple alloys (aluminum, zinc, and magnesium at CWM) and each has its own unique properties with advantages and disadvantages to each.   If your product requires post-finishing, it’s even more important to choose the right alloy because the physical properties of each alloy may or may not work with each type of finish.  Along with getting the right metal alloy recommendation, be sure that your die casting supplier fully understands all the finishing options available and can guide you to the right finish.  The die casting engineer must know all these variables from the project onset or it can result in costly quality issues later on.   Finishing can be a complex subject so we’ll talk more about it in another post.

Article on Selecting Best Die Cast Supplier for Aluminum, Magnesium, or Zinc


CWM created a 10-Point Checklist to Find the Right Die Caster to help OEM’s find the best metal die caster for their application.  There are many other important considerations than the few mentioned here.  Download the checklist from our Die Cast Design Center (DC2) and be prepared to ask all the right questions when you’re ready to choose a die caster for your next project.