A Low-Tech Solution for Cutting Moldmaking Costs
Machine-ready blanks have been available for decades, yet mold manufacturers have been slow to adopt them, even though they can save as much as 30 percent off overall mold and mold component costs and free up machine time for creating more in-house capacity.
Using machine-ready blanks (e.g., blanks that have been cut and precision ground on all six sides) eliminates the need to adjust setups and fixture offsets for each blank. In turn, this minimizes variation from part-to-part and increases part-to-part repeatability. Since the cost of machine-ready blanks is more than offset by labor and machine time savings, machine-ready blanks always reduce the overall cost of parts.
Benefits of Machine-Ready Blanks
Typically, mold manufacturers begin with raw stock sawed to rough dimensions. Before it can be finish machined into a mold component or a mold base, it should be machined to exacting tolerances on six sides. Often to reduce cycle time and cost, manufacturers machine the top and bottom only. Later in the process, this causes additional non-productive time, such as resetting fixture offsets, tool changes and part handling time.
When purchasing a machine-ready blank, it should come to your shop at specified net, close tolerances—ready to load, lock and go. Machine-ready blanks need no further prep and very minimal setup time before beginning value-added finish machining. The time and cost that are saved can be up to 30 percent or more.
Many manufacturers do not want to pay the additional cost for a machine-ready blank, instead preferring to purchase raw stock, saw it and rough machine it in-house. Because in-house blanks are generally not as consistent part-to-part as machine-ready blanks, they result in additional time spent on resetting fixture offsets, additional part handling and tool changes. All of this time ends up costing the manufacturer substantially more, as much and sometimes more than 30 percent of the completed component cost. Plus machines are tied up performing non value-added operations, when they could be making more components and molds.
The reason making machine-ready blanks in-house takes so much time and costs more is because they require specialized equipment and processes (see Specialized Equipment for Machine-Ready Blanks sidebar below), which cannot be justified. Tolerances of some machine-ready blanks can be as close as ±.0005" dimensionally and ±.0002" flatness, squareness and parallelism. The specialized equipment includes double-disc grinders, Blanchard grinders and duplex milling machines.