How to Design an Blister Molding Mold
Apr 01,2022
Blow-molding molds are something we see and use all the time, yet many people assume their design is straightforward. But do you really know how to design them? Let’s take a look at the key considerations during the design process.
I. Mold Opening Direction and Parting Line
At the design stage, each blister‑molded part must first have its mold‑opening direction and parting line determined to minimize core‑pulling slider mechanisms and eliminate any visual impact from the parting line.
II. Draft Angle
1. An appropriate draft angle can prevent surface fuzzing (stringing). For smooth surfaces, the draft angle should be ≥0.5°; for fine‑textured (sanded) surfaces, it should exceed 1°; and for coarse‑textured surfaces, it should exceed 1.5°.
2. An appropriate draft angle can prevent damage to the product’s top surface, such as whitening, deformation, or cracking.
3. When designing deep-cavity parts, the draft angle of the outer surface should be greater than that of the inner surface whenever possible, to prevent core shift during thermoforming, achieve uniform wall thickness, and ensure adequate material strength at the part’s openings.
III. Product Wall Thickness
1. All types of plastics have a specific wall-thickness range, typically between 0.5 and 4 mm. When the wall thickness exceeds 4 mm, it can lead to prolonged cooling times and shrinkage issues; therefore, revising the product design should be considered.
2. Uneven wall thickness can lead to surface shrinkage.
3. Uneven wall thickness can lead to porosity and weld marks.
IV. Reinforcing Ribs
1. Proper use of stiffeners can enhance product rigidity and reduce deformation.
2. The thickness of the reinforcing ribs must be ≤ (0.5–0.7) × the product wall thickness; otherwise, surface shrinkage may occur.
3. The single-sided slope of the stiffener shall be greater than 1.5° to prevent damage to the top.
Blow-molding molds are something we see and use all the time, yet many people assume their design is straightforward. But do you really know how to design them? Let’s take a look at the key considerations during the design process.
I. Mold Opening Direction and Parting Line
At the design stage, each blister‑molded part must first have its mold‑opening direction and parting line determined to minimize core‑pulling slider mechanisms and eliminate any visual impact from the parting line.
II. Draft Angle
1. An appropriate draft angle can prevent surface fuzzing (stringing). For smooth surfaces, the draft angle should be ≥0.5°; for fine‑textured (sanded) surfaces, it should exceed 1°; and for coarse‑textured surfaces, it should exceed 1.5°.
2. An appropriate draft angle can prevent damage to the product’s top surface, such as whitening, deformation, or cracking.
3. When designing deep-cavity parts, the draft angle of the outer surface should be greater than that of the inner surface whenever possible, to prevent core shift during thermoforming, achieve uniform wall thickness, and ensure adequate material strength at the part’s openings.
III. Product Wall Thickness
1. All types of plastics have a specific wall-thickness range, typically between 0.5 and 4 mm. When the wall thickness exceeds 4 mm, it can lead to prolonged cooling times and shrinkage issues; therefore, revising the product design should be considered.
2. Uneven wall thickness can lead to surface shrinkage.
3. Uneven wall thickness can lead to porosity and weld marks.
IV. Reinforcing Ribs
1. Proper use of stiffeners can enhance product rigidity and reduce deformation.
2. The thickness of the reinforcing ribs must be ≤ (0.5–0.7) × the product wall thickness; otherwise, surface shrinkage may occur.
3. The single-sided slope of the stiffener shall be greater than 1.5° to prevent damage to the top.
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How to Design an Blister Molding Mold
Blow-molding molds are something we often see and use, yet many people assume their design is straightforward. But do you really know how to design a blow-molding mold? Let’s examine the key considerations during the design process. ### 1. Mold Opening Direction and Parting Line At the outset of designing any blow-molded product, it’s essential to determine the mold opening direction and parting line. This ensures minimal reliance on core‑pulling mechanisms and eliminates visible parting lines that could affect the product’s appearance. ### 2. Draft Angle 1. An appropriate draft angle helps prevent surface defects such as stringing or fuzziness. For smooth surfaces, the draft angle should be ≥0.5°; for textured (sanded) surfaces, it should exceed 1°; and for rough-textured surfaces, it should be greater than 1.5°. 2. Proper draft angles also help avoid top‑surface damage, including whitening, deformation, or cracking at the product’s apex. 3. When designing deep‑cavity products, the outer surface draft angle should ideally be steeper than the inner surface draft angle. This prevents core misalignment during molding, ensures uniform wall thickness, and maintains material strength at the product’s opening. ### 3. Wall Thickness 1. Different plastics have specific recommended wall‑thickness ranges, typically between 0.5 mm and 4 mm. If wall thickness exceeds 4 mm, cooling times become excessively long and shrinkage issues may arise; in such cases, consider revising the product’s geometry. 2. Uneven wall thickness can lead to surface shrinkage. 3. Irregular wall thickness may cause porosity and weld lines. ### 4. Reinforcing Ribs 1. Appropriately applied reinforcing ribs enhance product rigidity and reduce deformation. 2. The rib thickness must not exceed 0.5–0.7 times the product’s wall thickness; otherwise, surface shrinkage may occur. 3. The single‑side slope of reinforcing ribs should be greater than 1.5° to prevent top‑surface damage. Blow-molding molds are something we often see and use, yet many people assume their design is straightforward. But do you really know how to design a blow-molding mold? Let’s examine the key considerations during the design process. ### 1. Mold Opening Direction and Parting Line At the outset of designing any blow-molded product, it’s essential to determine the mold opening direction and parting line. This ensures minimal reliance on core‑pulling mechanisms and eliminates visible parting lines that could affect the product’s appearance. ### 2. Draft Angle 1. An appropriate draft angle helps prevent surface defects such as stringing or fuzziness. For smooth surfaces, the draft angle should be ≥0.5°; for textured (sanded) surfaces, it should exceed 1°; and for rough-textured surfaces, it should be greater than 1.5°. 2. Proper draft angles also help avoid top‑surface damage, including whitening, deformation, or cracking at the product’s apex. 3. When designing deep‑cavity products, the outer surface draft angle should ideally be steeper than the inner surface draft angle. This prevents core misalignment during molding, ensures uniform wall thickness, and maintains material strength at the product’s opening. ### 3. Wall Thickness 1. Different plastics have specific recommended wall‑thickness ranges, typically between 0.5 mm and 4 mm. If wall thickness exceeds 4 mm, cooling times become excessively long and shrinkage issues may arise; in such cases, consider revising the product’s geometry. 2. Uneven wall thickness can lead to surface shrinkage. 3. Irregular wall thickness may cause porosity and weld lines. ### 4. Reinforcing Ribs 1. Appropriately applied reinforcing ribs enhance product rigidity and reduce deformation. 2. The rib thickness must not exceed 0.5–0.7 times the product’s wall thickness; otherwise, surface shrinkage may occur. 3. The single‑side slope of reinforcing ribs should be greater than 1.5° to prevent top‑surface damage.
How to Properly Maintain Rubber Molds
Every object has a finite lifespan, and to extend its service life, we must understand the proper maintenance procedures. Below are the correct methods for maintaining rubber molds. First, the wear curve of regularly maintained molds exists for every mold. Mold maintenance focuses on addressing abnormal wear that occurs during operation, and the number of stamping cycles completed during this period is easy to track. Once the predetermined cycle count is reached, a maintenance plan can be implemented, making it straightforward to identify maintenance tasks and manage maintenance timing. Second, enhanced maintenance aims to prolong mold life, ensure consistent quality, and simplify upkeep by refining specific mold components through targeted improvements. Third, routine maintenance involves standard cleaning and inspection of rubber molds, as well as lubrication with oil or similar substances. This work typically ensures the mold remains in good working condition, enabling early detection of any abnormalities. Fourth, when rubber molds experience malfunctions during processing—resulting in issues such as excessive burrs, incorrect dimensions, surface defects, or even burnt mold parts—they can no longer function safely. Such abnormalities necessitate immediate repair and maintenance, which is referred to as “accident‑related maintenance.” This type of maintenance is usually performed when the mold is nearing its operational limits; if the cost of maintaining the mold becomes prohibitive, its useful life may be short. Because such repairs often occur unexpectedly, it is essential to have contingency plans in place, including scheduled shutdowns and emergency response procedures.