Chair Injection Mould

What is the expected running cycle time for the chair mold?

The expected running cycle time for a chair mold varies due to several factors, including the type of material used, the complexity of the mold design, the size and wall thickness of the part, the production technology, and the efficiency of the cooling system.

• Standard Cycle Time: For most chair molds, the cycle time can range from 30 seconds to 3 minutes per cycle.
• Simple Designs: Simple chairs or parts may have a cycle time closer to the 30-60 second range.
• Complex Designs: More complex chairs may take anywhere from 1 to 3 minutes per cycle.

How do we make the parting line finishing is good, if there will is any sharp edges?

Sharp edges on the chair can pose safety risks, so it's essential to address several factors during the chair mold manufacturing process to avoid them:

• Parting Design: Ensure the chair mold parting design is correct.
• Cavity and Core Thickness: Verify that the thickness of the cavity and core is sufficient.
• CNC Milling Process: Consider how the CNC milling of the cavity and core is performed. Do you use a single-stage or multi-stage finishing process? Typically, three stages are needed:

1. Rough Milling: Start with rough milling before hardening the steel.
2. Half-Precise Milling: After hardening, proceed to the second stage, known as half-precise milling, where a tolerance of 0.3mm is typically left.
3. Final Precise Milling: After allowing the steel to stress release, conduct final precise milling.

Is the wall thickness uniform throughout the mold?

Hand working on the parting line is also one of the reasons for uneven wall thickness. However, the main reasons are still the 3D design of the plastic chair and the insufficient polishing of the cavities and cores. Therefore, when we start designing the plastic chair, we must consider the wall thickness. Sometimes, to ensure that the chair is strong enough, we need to increase the wall thickness in certain areas, but this requires careful consideration. Uneven wall thickness can lead to unbalanced injection and uneven cooling time, which will affect the injection speed and may cause shrinkage marks. If the CNC milling is too rough, it will be impossible to ensure uniform wall thickness in the chair. Our molds undergo high-speed and precise CNC machining, with three processing steps to ensure the accuracy of the chair molds.

How we can make the chair mould with less weight but strong enough?

When designing a plastic chair, it's essential to balance weight and strength. You can enhance the strength of the bottom area by adding more ribs. But what about the legs, backrest, and armrests? For these parts, you'll need to calculate or analyze the forces acting on each area. To achieve a lightweight yet sturdy chair, consider using a low MFI polypropylene material. However, this requires the mold to be very robust, and you must ensure that the injection filling is effective, especially since you're working with a material that has an MFI of 4 or a maximum of 6.