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In the process of selecting a mold, most people pay more attention to certain details, such as the core and cavity. But the wrong mold base can severely limit a mold’s productivity. Proper attention to choosing the base itself will lead to greater profitability and cost-effectiveness, which is why we’re providing you with the following information about mold base selection.

Moldbase Comparison Table Download

Mold Base Styles

Standard Styles

• A-Style – This four-plate design is the most common. Moldmakers will typically machine through pockets in the "A" and "B" plates to accept just about any kind of core and cavity insert.
• B-Style - A two-plate economy version of the A-Style. These are best used when part design can be machined directly into the cavity plates. Its compact configuration is also useful whenever overall mold height is limited.

Special-Purpose Mold Bases

• X-Style – A three-plate base, the stripper ("X") plate engages the edge of a part and pushes it off the core. The X-style is typically used when molding round parts like cups, caps and containers.
• AX-Style – Similar to an A-Style, but used for parts requiring core detail in the cavity side of the mold. When the mold opens, the core detail is pulled so the part remains on the ejector side of the mold.
• T-Style - This three-plate mold base operates with two parting lines and is used to separate the part from the runner in a tool. This configuration allows runners to be ejected separately from the part being produced.

Know Your Steel Types

• No. 1 steel - Machines easily and permits faster, smoother cutting. Best for short-run, low-cavitation production.
• No. 2 steel - Ideally suited for retaining multiple cavity and core inserts for medium to long production runs.
• No. 3 steel - Exceptionally clean and easily machined and polished. Ideal for cutting core and cavity details directly into the mold plate.
• No. 7 steel – Best for humid environments, corrosive plastics or clean-room requirements. Stainless, easily machined and corrosion resistant.

Machine Considerations
Choosing the right mold base is not just about the part; the molding machine also comes into play. What type of machine will it run on? What are the volume requirements? Does the mold have a mold action device? What kind of ejection does it need? In addition to these questions, consider:

• Height - Determine mold-base height based on the maximum daylight available in the press.
• Stroke - Consider the maximum stroke required to eject the part from the mold.
• Locating ring – Must match the platens of the machine where the mold will be running. The most common size is 3.99-inch OD.
• Sprue bushing: Orifice and radius of the sprue bushing must match the machine nozzle. Use a high-conductivity, copper-alloy bushing when sprue weight > part weight, when using sprue pickers or when minimizing scrap.
• Clamp-slot: Must be compatible with the thickness of the top clamping plate on your mold base. Quick-change systems may require special bolster plates or a unique clamp slot.

Consider Supplier’s Capabilities
Just as important as finding the right steel and mold base style is having the right supplier. Look for these value-added offers that save you time and money.

• Off-the-shelf availability, same-day shipment or quick delivery programs allowing you to receive you mold bases on time, keeping your delivery dates for your customers.
• Special machining capabilities can help smaller shops that don’t have the volume or resources to get a big bore mill and larger shops that don’t want to assign time and equipment to mold base machining. Every shop benefits by having more time to concentrate on cavity and frame work.
• Contour roughing services allow moldmakers to receive bases with nearly 90 percent of the material cut out for the part without the need for an insert, again saving valuable time.
• Parting-line preparation requires special tools and resources that many shops don’t have. Mold base suppliers should be able to provide that service.

To talk to a D-M-E mold base specialist in your area, please call 800-626-6653(U.S.) or 800-387-6600 (Canada) or email Customer_Service@dme.net. D-M-E is proud to be an essential resource to moldmakers and molders by providing them with mold bases and advice to meet increasingly demanding lead times and cost challenges. Visit www.dme.net to learn more.