Considerations for Product Development and Production Costs
Spurred by changing consumer demands, many of today’s high-volume markets are trending toward plastic containers instead of containers made of other materials. This means blow mold design has to meet more robust production requirements, while maintaining product quality and mold durability.
Prouct Development: First Identify Needs
To set up a successful blow mold production process, the first step is to define your critical part and production requirements by identifying a few key aspects of your part—in particular, symmetry, corner thickness, trim, and cooling time. Part complexity and volume have an important bearing on the most effective and least costly blow mold design to meet these needs.
Is your part symmetrical?
When a part is asymmetrical, we need to pay close attention to the way the part will eject, because the two halves of the mold cavity do not reflect each other. This causes the mold to release the plastic at different rates on different sides of the part, so we need to make allowances to achieve a clean part release. The asymmetry of a part also can affect wall thickness distribution, so we need to watch for areas that could be getting too weak or too bulky.
Does your part include tight radiuses?
Tight radiuses result in areas thinner than the main body, which can make them weaker. Wherever possible, large, smooth radiuses should be used to help maintain part integrity throughout the piece.
Will the plastic parison remain captive in the cavity or flash outside of the cavity?
A parison that remains captive results in a more attractive and more cost effective part. A part that must be flashed outside the cavity is costlier due to the addition of beryllium copper pinch plates, which adds additional costs to the mold and will require additional maintenance. However, flash is unavoidable with some parts when you need to obtain proper wall thickness distribution to outlying areas. An example of such a part would be a spray bottle with a wide base and small neck opening. The parison must flash outside the neck opening, in order to get proper wall thickness in the body of the container.
Many factors contribute to the cost of producing a part, such as multiple mold cavities, cooling times and materials.
Mold Cavity Size and Number vs. Production Needs
The size and number of cavities in a blow mold are largely determined by your output needs, and these are the primary factors in calculating mold cost. What is the anticipated annual volume of your product? More cavities generally return a lower piece price over time. However, additional cavities cost more at the outset of a project. Chances are that minimum order requirements and/or setup charges will increase with the number of cavities.
Designing for Optimal Cooling Time
The next major consideration of production cost is mold cooling design. Molds are constructed with internal water paths to cool the part with chilled water. Until the part has solidified, it cannot be ejected from the mold, so cooling directly affects cycle time. A well-designed mold that properly cools the part decreases the time the part must stay in the mold, reducing overall cycle time and ultimately reducing the cost of the part.
Filler masterbatch materials: cost – effective
Filler masterbatch under the name Europlas can offer a solution for reducing the production cost. It made by resin and more than 70% Cacium carbonate and some additvies, that’s why it is solusion for cost-effective for blow molding.
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