Industry / Association / Community Activity

Chicago White Metal further strengthens its ties with Village of Bensenville by offering an exclusive tour of the CWM facilities.  The relationship between Bensenville and CWM has existed since the 1970’s, when the company moved from its Chicago location and built the Bensenville plant.  About 1 1/2 years ago, CWM was featured on the Village of Bensenville local TV show, “Made In Bensenville,” in which Mayor Frank Soto and Eric Treiber discussed the manufacturing industry, the history of the company, the current state of die casting, corporate culture, and other issues.

Mayor Soto was accompanied by new Village Manager Evan Summers and Marketing & Business Development Administrator Mike Martella.

Chicago White Metal does it again!  To add to the collection of die casting awards, CWM teamed up with A-Dec to create a part that fulfills and exceeds the high standards and quality of A-Dec’s parts, which ultimately became an award-winning duo.

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.”

A-Dec produces high-end dental products with exceptional quality.

This Award of Excellence is an annual award that is given to the company demonstrating an outstanding example of the use of magnesium.  With the rear housing and driver die castings being the first magnesium parts to be used in A-Dec’s LED Operatory Dental Light, the benefit of a decreased mass, ease of movement, and satisfaction of the customer proved to be a winner in itself, even without the award.

When asked why a magnesium die casting was chosen for this application, a presentation given by Jon Miller a the Closing Banquet said the following:

“Magnesium’s strength-to-weight ratio and thin-wall casting capability allowed for a thin-walled, lightweight part, which in turn allowed for a slender, stylish, ergonomic support structure.  Magnesium’s low mass enables the LED light to be easily maneuvered/positioned and minimizes issues with drift, inertia, or vibration.  Magnesium’s ability to dissipate heat allowed for passive cooling of the circuit board and diode connection points.  This means fewer moving parts and helps the unit achieve an estimated 20-year service life.  Magnesium’s ability to be die cast with excellent surface finish, and to readily accept commercial RoHs-compliant pre-treatment and powder paint allowed the light housing to have a highly cosmetic appearance, matching the uniformity of the mating molded plastic and painted tubular structure.”

Congratulations to CWM and to A-Dec for amazing teamwork on this magnesium die casting duo!  

Miniature zinc die casting is a precision die casting process that addresses the need for smaller component production.  The process is similar to conventional hot chamber die casting, but has the ability to produce castings with faster cycle times, tighter tolerances, and minimal value-added operations.  It can also be an economical replacement for other processes such as screw machine or stamping.

These miniature parts can be cast with great precision in comparison to larger die castings. 

Thin walls, minimal flash, and ability to produce complex geometries are among the benefits of choosing miniature die casting for smaller parts.  Miniature die casting can be used in many different industries such as: medical, military/government, electronics, computers & peripherals, lawn & garden, alternative energy, telecommunications, global positioning services (GPS), lighting, consumer products, automotive, and many others. n also be an economical replacement for other processes such as screw machine or stamping.

Using four-slide machines and single cavity tools, cycle times are significantly faster than conventional die casting, yet still offer great accuracy and repeatability.  With a single cavity tool, tolerances of +/- .001 of an inch are possible on select features. This becomes a crucial advantage as die cast parts get smaller, as costly secondary machining can be avoided.  If larger volumes are required, it is not uncommon to utilize multiple cavity tooling.

For more information on miniature zinc die casting, visit our Mini Zinc Die Casting Page or e-mail us at sales@cwmtl.com.

OEM engineers as well as die cast engineers consider several factors when addressing the elements that are involved in metal die casting design.  One of the key elements in this process involves the geometry of the die cast part and how it relates to the placement of the parting lines.

What is a Parting Line?

An engineer within a die cast company knows that die casting dies must be constructed in at least two parts.  When the die is placed within the die cast machine, the two plates come together in order to form the two halves of the part, whether it is in aluminum, magnesium, or zinc alloys being used.

Around the perimeter of the part will be a visible line that runs exactly where the two die would meet.  This line is called the parting line. This line determines which half is the “cover” die and which will be the “ejector” die.  This also is a determinant of how the rest of the part will be designed in conjunction with additional processes.

Why is the Parting Line Important?

The parting line determines the overall design of the part in conjunction with the following considerations:

Cost Efficiency

• Reduction of flash formation
  • Elimination/reduction of trimming, hand filing, or additional flash removal processing.
• Elimination/reduction of machining.

Engineering Requirements

• Influences tolerances to be held in the area of the casting.  Tolerance standards must follow NADCA guidelines.
• Influences draft angles, wall thickness, and geometry considerations.
• Influences metal flow and casting integrity.

Cosmetic Appearance

• Designating a parting line to “flow” with the contours of the design will optimize the overall aesthetics of the die casting part.

Cosmetic Surface Finishes vs. No Surface Finishes

Surface finishes for die casting component design should be discussed in the pre-planning phase of the engineering of the part.  It is critical this discussion takes place beforehand because the location of the parting line, the gate, overflows, and vents, should accommodate and not blemish the finish of the part’s surface.

1) If cosmetic surface requirements are not a priority, the die casting component will be designed in a way where the die halves will utilize the most advantageous casting conditions as well as cost-efficiency.

2) If cosmetic surface requirements are a priority, the die cast engineer will work with you to incorporate design practices and additional processes to efficiently meet your needs.

Who makes the final decision on the Parting Line Location?

The die casting engineer should be the final decision maker on the location of the parting line when working with a metal die casting design.  Because the OEM designer may not be familiar with the importance of the parting line, it should be discussed with the die cast engineer to see what options are available.

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.

When 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.

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.

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.

Click here to view the .PDF

The 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:

• 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.