Integrating 3D Sand Printing Technologies Into Traditional Foundry Tooling Processes

Our First Live Webinar!!!

Hey, did you know that our first live webinar, hosted and moderated by the American Foundry Society (AFS), was broadcast on November 3, 2016?  Its true!  It was a lot of fun and a great experience.  Thank you to everyone that helped with the presentation and to those that attended.  If you were not able to make it to the live broadcast, you can still view the presentation in its entirety at: https://www.youtube.com/watch?v=2rJBDBHq0uI .

Drop us a line (or an email) and tell us what you think!

 

When Designing Castings, Don’t Get Shut-Out by Shut-Offs…and Other Pitfalls to Avoid.

Castings are considered highly engineered components that bring value to the end customer.  They are an economical way of solving difficult design related engineering challenges.  While casting technology has evolved over the years to deliver more capabilities to the foundryman, there are limitations of what can be done, both physically and cost effectively.

Designing Castings Using 3D Modeling Software

Using SolidWorks to Design a Casting

Care should be taken when designing castings so as not to inflate the cost of the part unnecessarily.  Minimizing complex or non-value added features, incorporating minimally aggressive parting line conventions and allowing for adequate draft are key factors to success.

Cores add cost to both the tooling and casting processes and should be reserved for situations when their use offsets the cost of additional machining operations.  Parting lines should be kept as flat, or planer, as possible.  Drastic changes in parting orientation or direction should be avoided.  These sharp transitions generate steep “shut-offs” in the mold, which can contribute to casting quality problems, excessive finishing costs and, in extreme cases, the addition of cores.

Draft needs to be present, but should not be excessive.  The amount of draft relief over the length of a feature is more important than the draft angle itself.  The number varies depending on equipment and process parameters.  In general, .030″ to .060″ (.8 to 1.6 mm) of draft should be a good starting point for most foundries.  However, in some situations the foundry will require more than this.  (i.e. blind holes & pockets, tight corners, deep parting offsets, etc…)

If specifying a draft angle, be aware that small numbers can add up fast.  A 10″ deep pocket with 3 degrees of draft will have over 1/2″ (12 mm) of draft material added.  This not only adds significant weight to the casting, but could also affect the solidification behavior of the casting which could lead to defects.

There are also different types of, or ways to apply, draft.  Traditional, radial and natural are all conventions used to streamline the tooling and casting process.  Application of and when and where to use each method is a skill that takes time and practice to master.

Be aware of draft convention and consider the effects of “plus draft”, or added draft, versus “minus draft”.  (“Plus draft” is usually considered the default unless otherwise specified.)  Plus draft will hold the dimension at the furthest point from the parting line and add material.  Minus draft will hold the dimension at the parting line and remove material from the casting.  This is usually reserved for situations where clearance to mating parts is of concern.

Working with the foundry and pattern shop to address these issues on the front end of the casting design will go a long way toward making your casting design a success.  Contact our team of skilled casting and CAD engineers to see how we can help you get your casting design started on the right foot!

 

The Importance of Material Validation for Prototyping

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Craft’s SPECTROMAXx spectrometer. Used for the chemical analysis of ferrous and non-ferrous metal casting alloys.

Verifying the materials you produce meet or exceed customer expectations is paramount to any product development program.  Expensive testing will be done and important decisions made off of the data produced, so it is imperative that test results are representative of the materials and products that will be made in production.  For this reason, you should expect, and even demand, that alloys and resins used in prototyping processes are representative of your production materials and processes.

Most metal alloys and plastic resin materials are at least partially specified by their chemical composition.  (There are some exceptions to this – the cast iron family of materials comes to mind.) Many alloys and resins are also subsequently modified via thermal processing (i.e. heat treat) or other mechanical means (i.e. cold working) in order to develop their final properties.

So long as the material produced and/or used in a process meets the specification chemical and processing requirements, predictable mechanical, thermal, electrical and physical properties will result.  A manufacturer of quality prototype parts will recognize this fact and will build robust processes that yield materials in line with customer expectations.

Metal casting, injection molding, thermo forming…the processes can all be prototyped using production grade materials and processes.  The trick is knowing what time compression techniques can acceptably be used in order to shorten the product delivery cycle.  Usually, this means some sort of “soft tooling” or integrating 3D printing technologies into the process, but not always.  The one rule, however, is that time compression should never come at the expense of the materials used to produce the parts.

New Material Offering: Ductile Ni-Resist

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Craft is proud to the announce the addition of austenitic ductile irons to our already diverse line of cast metal alloys.  Austenitic ductile iron, or commonly called “ductile ni-resist”, is used for parts requiring high resistance to heat, corrosion and wear.  Many of the ductile ni-resist grades are also non-magnetic.  In addition to the end use benefits mentioned, it offers a lower cost of manufacture versus comparable stainless steel materials.  .

For more information, please contact our team of technical casting experts to find out how this material can be a solution for your engineered casting needs!