Why Choose Contenti for Spin Casting?
With almost 50 years of experience in white metal casting, The Contenti Company has made a permanent commitment to quality and improvement in spin-casting and investment casting technology. Throughout the years, Contenti has expanded the use of spin-casting equipment for jewelry and other parts to include the casting of engineered, prototype, and industrial parts. Our acquisition of the Frank Pertot Company in 2000 has added two exclusive formulations to our selection of organic mold rubber.
Spin-Casting is an asset as a manufacturing process, allowing thermoset plastics, pattern waxes, and metals all to be cast effectively. Fast setting liquid thermoset plastics can be spin-cast as an alternative to injection molding. Plastic production parts can now be manufactured economically when injection molding isn’t cost effective. Pattern wax can also be spin-cast to create wax patterns for investment casting, greatly increasing productivity.
Die Cast Quality
The Contenti Company has always dedicated itself to development and research of new materials and processes for spin-casting. Contenti offers the highest quality tin and lead based casting alloys. These alloys, as well as other metals such as zinc/aluminum alloys, can be used in spin-casting to produce tens, hundreds, and even thousands of high quality production parts. Spin-Casting can offer die cast results in cases where die casting is cost prohibitive.
Manufacturing isn’t the only area benefiting from Spin-Casting. Rapid prototyping and product development is quickly finding Spin-Casting to be a strong ally. Engineers and product designers can create numerous quick, economical, and functional parts in high strength metal or plastic from delicate stereo-lithography models. Molds can be made and parts can be cast in as little as 3 hours, or for complex parts, rarely more than one day. Design changes in size, function, fit, or appearance can be quickly reproduced without making or wasting a large investment in tooling and machine time.
The Spincasting Process Explained
Preparing The Mold
Choose an appropriate mold rubber based on your needs. Place your models on the uncured rubber disc, using a pair of dividers to ensure a balanced mold. Insert a center plug into the middle of the rubber disc and arrange locknuts to ensure proper alignment of the two mold halves. Place the rubber disc in a ring frame and dust with mica powder before adding the second mold half.
Vulcanizing The Mold
Preheat your vulcanizer and mold frame to the correct temperature before inserting the mold. Place the mold frame into the vulcanizer and slowly increase the pressure on the mold using the jack to raise the lower platen. As the pressure increases and the heat is transferred from the vulcanizer platens to the mold, the rubber flows around your models, filling every void and capturing every detail.
Gating and Venting
Once the rubber mold has been vulcanized, removing your models is as easy as removing the mold frame set from the vulcanizer and flexing the rubber mold. Gates are now cut into the rubber mold to direct the molten metal into the model cavities during casting. In addition, vents are cut into the mold to prevent the buildup of gases. The gates and vents are easily cut using a sharp knife and are specifically shaped to take advantage of the spin casting process.
With all of the gates and vents cut, the mold is placed into the spincasting machine. Adjustments are made for table spin speed, cycle duration, and clamping pressure and the cycle is starting by simply closing the lid of the spin casting machine. Molten metal is then poured into the funnel at the top of the machine. The centrifugal force created by the spinning of the casting table forces the molten metal into all of the cavities within the mold. The result is a perfectly cast part which retains all of the detail of the original model, right down to the surface texture.
If done properly, the cast parts can be snapped off at the gates without the use of tools and should require little or no finishing.
Frequently Asked Questions
What do I need to get started?
The three major pieces of equipment needed for spin casting are: Vulcanizer, Melting Furnace, and Spin Casting Machine. The approximate cost of this equipment is under $12,000.00 (not including freight charges). Additional items such as mold rubber discs, casting alloy, and other tools are also needed. The pricing on these items depends on your specific needs. See The Basic Setup for more information.
Can I purchase used equipment through Contenti?
Yes, The Contenti Company sells a variety of used equipment. All used equipment undergoes a thorough inspection and are completely refurbished before leaving our facility. We provide complete customer support for all used equipment purchases in addition to a 30 to 180 day warranty on parts. Please contact us for more information on what equipment is available.
Which mold rubber should I use?
Each mold rubber compound sold by The Contenti Company has unique characteristics which make it well suited for certain applications. The durometer, flexibility, tear resistance, and temperature resistance of each compound affects the quality of the mold and the parts cast from it. Factors which should also be considered are: the size of the patterns to be cast, complexity of the patterns, and the material being cast. The size of the rubber disc depends on the size of the pattern. For more information, see our Mold Rubber Comparison Chart.
If casting in metal, what alloy should I use?
Like rubber compounds, all alloys are not alike. When choosing an alloy, several factors should be considered. Some of these factors are: complexity and detail of the patterns, size, application (will items be used to hold food/ beverages?), and cost. For more information, see the Casting Alloy page.
Can I cast other materials besides metal?
Yes. Although zinc, tin and lead alloys are the most common materials cast using the spincasting process, other materials such as wax, resin, and thermoset plastics can also be used. These materials can be used in the same silicone rubber molds used for casting metal.
Is extensive training needed to achieve good results with spin casting?
No. The techniques required to produce a basic rubber mold can be mastered in an afternoon. More complex molds, with undercuts and removable cores, require more practice. The casting process requires very little training.
How many pieces can be cast in an hour?
For maximum efficiency, several molds should be used in rotation when spin casting. Using multiple molds allows each mold time to cool before it is cast again. A rate of 30 to 60 cycles per hour is average when using a sufficient number of basic molds (containing parts which are small and relatively flat). The total number of parts which can be cast in an hour is a function of their size and complexity.
What is the average life span of a spin casting mold?
Spin casting molds which contain small relatively flat parts can last as long as 1000 casting cycles. Molds containing larger, heavier parts and those cast in zinc alloy have a somewhat shorter lifespan. The type of rubber compound used to make the mold and the material being cast into it will also effect the life span of the mold.
How does spin casting compare to die casting and other methods of reproduction?
The greatest advantage of spincasting over die casting and most other processes is the low cost of mold making (tooling). The lower costs make it economical to cast items in very low quanties. Design changes can also be made to parts after they have been cast, then another mold made to "perfect" the design. And you don't lose out on cost savings when casting large quantites of parts. Per part costs are similar to die casting.
How much finishing is required for spin cast parts?
If your spin casting mold is well-made, the cast parts can be easily snapped off at the sprue by hand. Finishing the parts will depend on the desired final appearance. Typically, spin cast parts are run through a Vibratory Finisher, when necessary, to smooth die lines, remove any burs, and smooth imperfections. Since the die lines and sprues of spin cast items are small, finishing time is minimal and often unnecessary. A reflective surface is attainable by finishing the piece on a polishing lathe.
What final finishes can be applied to spincast parts?
Finished parts can be: electroplated, antiqued by darkening the casting with an oxidizing agent and buffing the raised surfaces, or inlaid with colored epoxy.