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Tactics for Optimal Product Design for Die Casting

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Developing an optimum product design for die casting is similar, in most respects, for any material/process combination. In capitalizing on today’s advanced die casting processes, however, specific attributes of die casting alloys and the die casting process offer opportunities for distinct product advantages and cost reductions that require somewhat different tactics. These should be applied when a totally new product is being developed, and are critical when an existing product made from another material or process is being redesigned for die casting.

An engineer going over a CAD design for custom die casting designWhen a custom die casting design (or any design) is started from a clean sheet of paper, the designer must disassociate the design constraints from the materials and processes traditionally employed. This is the path to the optimum cost-effective results. Three principles are helpful:

• Think function, before traditional form.
• Performance must be sufficient, not equal.
• Match material properties to performance specifications.

Function Before Traditional Form
In many cases form does not reflect function, but is instead determined by the traditional material and process employed. Therefore, it is essential to think of the function(s) that the component is to perform, and disregard the traditional or previous process form. For example:

• A powdered metal part may have relatively thick walls in structural areas, with throughholes to remove excess material. A die casting typically achieves maximum structural properties by utilizing thin walls with corrugated sections or rib reinforcements.

• An injection molded plastic component may be attached with through bolts and nuts, which are required because the viscoelastic (relaxation) behavior of the plastic makes it necessary to apply only compression loads. Or it may utilize metal inserts. A die casting with superior creep and relaxation properties can employ tapped threads to an advantage.

• A billet machined part may have block like features to obtain functions, for example: square pockets, sharp edges, flat and cylindrical surfaces. The same part designed as a custom die casting may obtain function with smooth filleted pockets, generously radiused edges and contoured and shaped surfaces.

The function before traditional form principle can often be applied to die castings made a few years ago. In many cases, wall thicknesses have been dictated by the limitations of then existing casting technology, so that the die casting component was over designed in terms of functional and structural criteria. Yesterday’s die castings can often be redesigned and produced by today’s advanced, custom die casting technology with thinner walls, reduced draft, and closer tolerances that more nearly reflect the functional criteria.

It is important to note that the definition of form in “function before traditional form” is the traditional shape that is required by specific manufacturing processes. This is not to be confused with a purposely designed form or shape that may provide value or function to the product design. The die casting process easily produces complex design shapes that may be difficult, costly or impossible to produce with other manufacturing processes.
Zinc Magnesium Aluminum Die Casting Optimization

To read more, Chicago White Metal Casting published a technical paper titled, “Developing an Optimum Product Design, Capitalizing on Die Casting.”  The paper reviews two additional designing principles mentioned in this post: 1) Performance must be sufficient, not equal and 2) Match material properties to performance specifications.  The technical paper is available as a free download in our Die Casting Design Center (DC2) to any subscriber.  Subscribe now and download the technical paper.

Contact CWM today to discuss your custom die casting project!

Still Believe That Magnesium Die Casting is Too Expensive?

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Magnesium die casting floating moneyThe reality is, die casting metal materials are priced and purchased by the pound. In engineered part designs, their material content is based on the volumes actually used in the part. When objective material cost evaluations are based on “equal volume” comparisons, magnesium die casting becomes cost-competitive due to its low density, excellent strength, stiffness and energy absorption characteristics. Magnesium has the highest strength-to-weight ratio of any structural metal.

Magnesium’s thinwall die casting capabilities routinely allow housing walls to be cast to 0.12 in. (3 mm), with many walls cast as thin as 0.03 in. (0.76 mm). The results are lower magnesium part weights and material costs comparable to reinforced plastics. Automated hot-chamber magnesium die casting technology, exclusively used by CWM, delivers faster cycle times (30% greater than aluminum processing, plus die life from two to four times longer).

Cost and other so-called “knowns” about magnesium related to the die casting process may be keeping you from realizing the considerable benefits of today’s die cast processing in magnesium. Download CWM’s paper and get the facts on die casting with magnesium.  The paper is free to any Die Cast Design Center subscriber.

Explore the advantages of die casting with Magnesium and see if its unique properties can be employed in your new design or conversion from another process.  View our recorded webinar titled, “Magnesium Die Casting: Solutions for Today’s Markets.”  This 50-minute video reviews:


PREVIEW: Magnesium Die Casting Webinar
  • Mg properties and benefits
  • How Magnesium die casting stacks up to other manufacturing options
  • When Mg die casting is a smart choice
  • Prototyping and finishing options
  • Loads of case studies!

The webinar is available to any subscriber of CWM’s Die Casting Design Center – DC2.  Subscription is free and offers 75-plus technical papers including die cast design assistance, design specifications, and component sourcing resources. View the webinar now.  

CWM Wins 2013 NADCA Casting Competition

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For the third year in a row, CWM won an award in NADCA’s annual International Die Casting Competition. In 2013, CWM won in the Magnesium Over 2 lbs. category for a projector housing.


Watch the interview with Rob about the
magnesium component here!

Rob Malarky, CWM Engineering Project Manager, worked with our customer’s engineering team to convert two magnesium components into a single unit. Internal features of this magnesium die cast part were redesigned to make it simpler and easier to manufacture. After the redesign, the customer gained a 40% cost reduction. This was realized by eliminating a second casting, die trim, additional machining and dowel pin insertion. The magnesium die cast part also incurred an 8% weight reduction due to the change in geometry.  Rob talks about the process in this exclusive interview, also located on our YouTube channel.

View the PDF case study, available in CWM’s Die Cast Design Center.

Speak with a CWM representative today about your magnesium die cast project!

 

Fresh Website Redesign Offers Product Design Resources to Engineers

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Chicago White Metal justCWM Website - New Die Cast Resources unveiled its redesigned website, www.cwmdiecast.com.  The website will serve as a resource for OEM product designers, engineers, design consultants, purchasing managers and buyers of die cast components.

The new website features two relevant sections: information about Chicago White Metal’s operations and the Die Cast Design Center (DC2), a free educational hub with one of the industry’s largest collection of technical die cast resource content.  Its purpose is to assist design engineers and buyers through the die casting design and purchasing processes.

“Completely redesigning Chicago White Metal’s internet presence was a large undertaking,” said Marketing Manager, Sandy Winkelman. “The new enhancements will be more informative and offer a superior experience for our visitors. The site reflects our commitment to provide visitors with relevant content that will assist them in every aspect of die casting product design in addition to assisting buyers through the purchasing phase.”

Simplified site navigation makes it quick and easy for the visitor to find information and answers to their questions. A new ‘Ask an Engineer’ feature allows visitors to send questions directly to a die casting engineer to get personalized assistance.

aluminum magnesium zinc die cast design center

Other website features include:

  • A new blog section with details on magnesium, zinc, and aluminum die casting
  • A totally reorganized Die Cast Design Center (DC2) with new die casting resource content
  • Links to multiple CWM social media sites
  • FAQ pages with eight different categories of die cast resource information
  • Rep locator with interactive map

Chicago White Metal has further plans to add new content including videos, case studies, webinar recordings and other reference material to engage visitors on an ongoing basis.  The site’s integration with social media provides additional options for the engineering community to access information and other die casting resources.

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

CWM’s DC2
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.