DC2 Loging

Category Archives: Designing

Die Cast Tooling 101

Published by:

This is an illustration of a die cast tooling die. The key to a successful die casting is a good tool design, so it is vital that both the die caster and the customer are well-versed in die casting capabilities and how they fit with project requirements.

A die casting die is a custom-engineered, multi-part piece of equipment made from high quality, heat-treated steel.  The tool is composed of two halves – a cover die (which is stationary) and the ejector die (which the die casting machine moves to meet the cover die).  As soon as the two halves meet, the molten metal is injected into the tool, where it is held under pressure until it solidifies.  After solidification, the metal is ejected, creating a nearly net shaped part within seconds.

Before a die is built, the customer first presents a concept or existing part to a die caster.  A die cast engineer will assess the project from design to end product and work with the customer to optimize the part design for die casting.   An initial discussion with the die caster may include topics such as: functional and cosmetic requirements, tolerances, annual and lifetime volume, alloy choice, mating parts, project timing, optimizing wall thickness, adding ribs, draft and radius, etc.  Download a checklist of common considerations from CWM’s Die Cast Design Center (DC²):  NADCA Tooling Checklists for Die Casting Dies (2015).

Types of Die Casting Dies

Prototyping Dies

Prior to a full die cast production run, prototype parts can be created with a 3D printer using ABS plastic, or other rapid prototyping methods.A fully featured, custom production die is a significant investment, so a prototype die is often used to make a small number of castings to test the part in several different scenarios (with the end product, dimensional accuracy, etc.).   Prototyping strategies include 3D printed parts, machined hogouts, or gravity castings, but these involve tradeoffs on the design, tolerances, and properties.  A high pressure die casting prototype die is the best approach if you want the same properties, alloy, geometry, and process that will  be in place for production.

Prototype die casting dies can be produced in shorter lead times and at less cost because they can utilize standardized components (such as an existing die base and other components), and pre-hardened, uncoated tool steels.  They also require less engineering and may employ less efficient cooling or ejection techniques compared to other production methods.   The tool will not last as long and the die will not run as efficiently as a typical production die, but this is a non-issue when you only need a small quantity of parts (1,000 or less).    Design changes can be made faster and at less cost with a prototype die than would be the case on a custom, hardened/coated steel production die.   Parts made from a prototype die are generally hand cleaned of flash, avoiding the lead time and cost of a trim die.

Production Dies

Production dies are used when all designs are finalized, approved, and the program is ready to “launch” into an actual run.  These dies can have single or multiple cavities and the option of slides, depending on the design.  Read more about slides below, under “Casting Features and Die Considerations”.

Trim dies: In addition to the production die cast die, CWM employs trim dies for high volume production.  The trim die “trims” off the runner, overflows, and flash from the part, immediately after it is cast.  Some trim dies only require an open/close function, and others need multiple stations, cam, or hydraulically-operated motions to successfully remove all of the flash.   Occasionally, part geometry precludes the ability to completely remove flash with a trim die.  In that case, custom trimming devices, mechanical or hand de-flashing strategies will be employed.

This is an exploded view of a unit die insert that goes into a die cast tooling die.Unit Dies

A unit die is a special type of production die.  A common die-caster owned unit holder keeps the customer owned cavity block or unit die with cavity insert intact.   Single and double unit holders are common and come in a variety of sizes.   Typical sizes of the cavity blocks that they hold are 8”x10”; 10”x12”; 12”x15”; or 15”x18”.  Since unit dies employ generic components, they are often used for smaller, less complex parts with lower volume.   Larger, multiple slide, complex geometry, and higher volume parts are generally better served with a complete custom die that is engineered specifically for that part and allows for maximum efficiency and control.

Die Components and Terms

Some of the more common die components and terms include cavities (or cavity inserts), parting lines, cores or core pins, slides or slide cores, ejector plates and ejector pins.   A brief description of each follows:

Cavity Blocks or Cavity Inserts

These are the portions of the die casting die into which the part geometry is formed.   There is the ejector cavity (sometimes called the core cavity) and the cover cavity.   The cavity blocks are made of premium grade tool steel and are normally heat-treated to a very high hardness, then coated for lubricity and long life.   Water cooling lines pass through the cavity blocks as do the ejector pins that are used to push the part off of the die.   The cavity blocks are where most of the cost comes from, as generally this is where most of the custom design, engineering, and detailed machining is done.

Parting Lines

When the two die halves close, metal is injected into the cavity blocks and cooled in order to create the part.  There is a line that forms on the part where the cover half and the ejector half meet called the “parting line.”

More information on the parting line can be found in the following blog, “Read Between the Lines: Parting Line Placement in Metal Die Casting Design”.

Cores or Core Pins

A “core” is the separate and replaceable part of the die that forms an internal feature of the casting.   A core can be any shape, though circular is the most common (usually referred to as a “core pin”).   A core may be fixed to the die cavity or to a slide, actuated through the mechanical opening/closing of the die, or by hydraulic cylinder or other means.

Slides or Slide Cores

A slide (or slide core) is the portion of the die that forms a feature of the casting, that cannot be made with the normal opening and closing of the die, but is required to move at some angle relative to the parting line (with the most common orientation being parallel to the parting line).   The “slide” is the general term for the entire moving section, but a slide consists of multiple pieces (such as the slide front or tip, the wear plates, gibs, locks, carriers, etc.) and is generally water cooled.   Slide core is the general term used for either a simple core pin that is moving in and out on some angle to the parting line or a pin within the larger slide mechanism (for example: a replaceable “slide pin” can be mounted in the slide to form a specific hole, where the rest of the slide face forms the outside surface of the part).

Angle pins and hydraulic cylinders are the most common motion sources that activate slides.  Both sources of motion need to be designed into the tooling to avoid interference with part ejection/removal.

Angle pins are the more economical option because it is activated by the opening and closing of the die, and does not require hydraulics or switches, but is limited to shorter movements.   The hydraulic method offers a wider range of options including pull direction, timing of the pulling, and length of pull.   A die cast engineer can recommend the appropriate option based on the project.

These are ejector pins that are strategically engineered into a die cast tooling design.Ejector Plates and Ejector Pins

Once a part has been cast and cooled, the halves open up and reveal the cast part.  The part typically shrinks in size as it cools, remaining in the ejector half of the die.   Ejector pins that are driven by a moving ejector plate are activated and used to push the casting off the die.

The ejector pin leaves a slight imprint on the casting, which indicates the placement of the pin should be in a non-cosmetic surface area of the casting that is not critical to the design (overflow, boss, bottom of a deep pocket, bottom of a rib, etc.).  Ultimately, the number of pins, pin locations, and pin sizes are dependent on the configuration and size of the part, along with other requirements.

Contact a CWM Die Cast Engineer.

 Our engineering team is prepared to answer any questions you may have about the die casting process, as it pertains to your project.  Feel free to contact us directly at 630-595-4424, or e-mail us at sales@cwmtl.com in order to get in touch with the appropriate specialist.

Order a copy of the NADCA Product Specification Standards for Die Castings book.

Visit our Online Store and get an exclusive discount!

Design for Manufacturing – Die Casting

Published by:

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!

Published by:

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.

Aluminum vs. Magnesium vs. Zinc: Alloy Properties in a Nutshell

Published by:

Aluminum, magnesium, and zinc are the most common alloys used in the die casting process.  Aluminum and magnesium are considered to be relatively “lightweight” metals, and zinc alloys are a preferred metal to use in the miniature die casting processes and applications requiring thinner walls.

Deciding which alloy is best suited for a specific application of a die cast part is usually based on the design specifications – the alloy usually provides physical and mechanical properties that fit the end product application.  It is important for a product designer seeking a die casting supplier to understand each type of alloy being offered and what benefits are involved.

Aluminum Die Casting Alloy

Metal Die Casting Worker is hand filing an aluminum component at the parting line.

Aluminum is by far the most frequently used alloy in die casting.  The most common aluminum die casting alloy is A380, which offers the best combination of material properties and castability.  Aluminum alloy die castings are used in a wide variety of industries.  It is common to see this alloy in electronics, communications equipment, automotive components, gear cases, lawn mower housings, hand and power tools, and many other products.

There are a number of aluminum alloys used in die casting.  Each alloy has its own unique set of properties.  Aluminum alloys for die casting have superior machining characteristics in comparison to iron, steel, and titanium.  Amongst the other types of aluminum alloys, A380 has better than average machining characteristics.

Aluminum die casting alloy informational sheet from NADCA.

For more information on Aluminum Alloys for Die Casting:
Click Here to Register and Download “NADCA Alloy Data: Aluminum Alloys” White Paper.



Magnesium Die Casting Alloy

Magnesium alloys are Magneisum die casting used as a Kodak camera housing.the lightest of the commonly used structural metals used for die casting.  Magnesium alloy AZ91D offers the highest strength of all commercial magnesium die casting alloys.  It is also the most widely used.  AZ91D Magnesium is a high purity die casting alloy which offers the following qualities:

–          Excellent Corrosion Resistance

–          Excellent Castability

–          Excellent Strength

Corrosion resistance is achieved by enforcing strict limits on three metallic impurities: Iron, Nickel, and Copper.

Some of the more common applications for magnesium die castings are:

Automotive: cam covers, steering columns, steering wheels, brake and clutch pedals, clutch housings, seat frames, and dashboard supports; Portable tools such as: chain saws, drills, grinders, lawn mowers, string trimmers and pruners; portable electronics such as: projectors, cameras, radar indicators, calculators, and navigation devices; telecommunications equipment, levels; and recreational products such as: snowmobile components, archery bows, spotting scopes, etc.

While there are special precautions to take when machining or grinding magnesium die castings, magnesium alloys machine easily, requiring less power to machine than the other die casting alloys.

Finishing magnesium castings is similar to other alloys and any special treatments and coatings are usually taken into account when considering the end product and application.

magnesium alloys for die casting - information sheet from NADCA.  For more information on Magnesium Alloys for Die Casting: 
Click Here to Register and Download “NADCA Alloy Data: Magnesium Alloys” White Paper.


Zinc and ZA Die Casting Alloys

Zinc and ZA alloys are Zinc and ZA Alloys have ingots and recycled zinc, ZA8, Zamak 3 die casting scraps.  commonly used for smaller die castings or die castings that require thinner sections.  Zinc alloys generally allow greater variation in section thickness and can maintain closer tolerances.  The impact strength of zinc die cast components are higher than the other common metal alloys, with the exception of brass.  Also, because Zinc and ZA alloys require lower pressure and temperatures in comparison to magnesium and aluminum alloys, the die life is significantly longer and maintenance is relatively minimal.

Zamak alloys all contain approximately 4% aluminum and a smaller percentage of magnesium to make sure strength, hardness, and corrosion resistance properties can be achieved.

When it comes to miniature die castings, zinc is definitely the route to take.  Miniature zinc die castings can be produced at high volume using special hot-chamber die casting machines that yield castings which are flash-free, with minimal draft and very close tolerances, requiring no secondary trimming or machining.

Zamak #3 is the most common of the Zinc alloys for die casting, offering the best combination of mechanical properties, castability, and economics.  These zinc alloy metals have the ability to produce castings that have intricate details and surface finish at high production rates.

ZA alloys have more aluminum and copper content in them than the Zamak group for several reasons:  higher strength, superior wear resistance, superior creep resistance, and lower densities.  ZA-8 is the sole ZA alloy that can be die cast by the faster hot-chamber process.

Machining characteristics of Zamak and ZA are very good and both alloys have the ability to accommodate high-quality surface finishes when routine guidelines for machining zinc are followed.

zinc, miniature zinc, ZA8, and zamak alloy groups explained in this NADCA information sheet about die casting alloys.  For more information on Zinc Alloys for Die Casting: 
Click Here to Register and Download “NADCA Alloy Data: Zinc and ZA Alloys” White Paper.



magnesium zinc and aluminum die casting engineer at work.

If there are any suggestions to be made to gain more information, it is this:  have that initial discussion with a die casting specialist or engineer regarding the product and its application!  This will increase the understanding from a product design standpoint in order to know what options are available and best for your product.


North American Die Casting Association. “NADCA Alloy Data: Aluminum Alloys,” “NADCA Alloy Data: Magnesium Alloys,” “NADCA Alloy Data: Zinc and ZA Alloys.”  NADCA Product Specification Standards for Die Castings. 9th ed. Vol. #402. Arlington Heights, IL: NADCA, 2015. N. pag. Print. NADCA Publication.

Chicago White Metal is the “face” of Manufacturing Technology at Harper College

Published by:

Eric Treiber, CEO and President of Chicago White Metal Casting, speaks freely on the subject of career opportunities in manufacturing for Harper College.  As a prime source of insight into the manufacturing sector, Harper included this video on their manufacturing technology page, making Chicago White Metal the “face” of manufacturing.  With a vested interest in assisting individuals with obtaining the proper manufacturing certifications, CWM provides Harper College a scholarship fund for students in need, which assists with the expenses of enrolling in Manufacturing technology courses.

As a representation of the die casting industry, Eric gives his perspective of the outlook on not only career opportunities, but also a rate of growth that CWM has experienced this past decade.  With 75+ years of experience in the industry and an amazing partnership with Harper College, Chicago White Metal enjoys being a part of an educational culture as well as within the die casting industry.

For more information on Harper College’s Manufacturing Technology pathways, visit: https://goforward.harpercollege.edu/academics/areas/manufacturing/mpc.php

Read Between the Lines: Parting Line Placement in Metal Die Casting Design

Published by:

Two halves of a die meet where the parting line exists on the metal die casting
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

Metal Die Casting Worker is hand filing an aluminum component at the parting line.

  • 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.

Need additional assistance with designing your Die Castings?

Aluminum Magnesium Zinc Die Casting Design Assistance

For further assistance on metal die cast design and parting line placement, register for or log into your account at dc2.cwmdiecast.com.  This resource for design assistance is at NO COST TO YOU and is entirely FREE to use.  Download PDF documents, past webinar presentations, and other resources that will prove useful in the die cast engineering process.

For additional resources online to assist with the engineering design of your die castings, you may also access our FREE Die Casting Design Center (DC2) for webinars, case studies, and other documents pertaining to all things die casting.