Injection Molding Key Points of Adjustable Support Foot Plastic Fittings

Adjustable plastic support feet are widely used in mechanical equipment cabinets, industrial equipment bases and modern furniture support structures. Relying on thread rotation to adjust the height, they bear long-term static load and vibration load, putting forward high requirements on product dimensional stability, thread matching accuracy and compression resistance. Due to the structural characteristics of thin base, thick threaded column and uneven wall thickness, defects such as thread shrinkage, warpage and creep deformation are prone to occur during injection molding, which need systematic process and mold control.

1. Material selection and drying pretreatment

According to the load demand, modified PP, ABS and glass fiber reinforced PA6 are selected as mainstream materials. Heavy-duty support feet adopt high-rigidity fiber-reinforced materials to improve anti-creep performance. Raw materials must be fully dried to eliminate moisture-induced silver lines and thread roughness. The proportion of recycled materials is strictly controlled to avoid reduced structural rigidity and long-term compression deformation. Batch material consistency is guaranteed to stabilize shrinkage rate and ensure uniform product size.

2. Mold thread structure and shrinkage design

The thread molding core adopts rotary core-pulling structure to avoid forced demolding and thread tooth damage. The mold shrinkage rate is set in combination with material anisotropy to compensate the dimensional difference between radial and axial shrinkage. The base corner is optimized with rounded transition to reduce stress concentration and compression cracking. The parting surface avoids the thread meshing area to prevent flash from sticking to the thread and causing adjustment jamming.

3. Gating system flow optimization

Side gate or submarine gate is arranged at the base position to avoid direct impact of melt on the thread structure, reduce shear stress and prevent thread deformation. The flow channel balance is optimized to ensure uniform filling of each cavity of multi-cavity molds, consistent thread size and good product interchangeability. The gate residual material is strictly controlled to avoid secondary trimming damage to the product base.

4. Uniform cooling and anti-warpage control

A surround-type cooling water path is adopted for the threaded column and base to solve the quality problem of inconsistent cooling caused by uneven wall thickness. The thick-wall thread part is strengthened with cooling to reduce internal stress and avoid post-demolding deformation and thread deviation. Stable mold temperature control reduces product shrinkage difference and effectively improves base warpage and thread column deflection.

5. Demolding and process parameter control

Uniform multi-point ejection is adopted for the base to avoid top deformation and top white defects. The threaded core is rotated and demolded at a constant speed to ensure complete thread profile. The injection speed is graded and controlled, with low-speed filling for thick walls to eliminate trapped air and moderate speed for thin walls to ensure full filling. Reasonable pressure holding and cooling time are set to balance shrinkage and improve product compression resistance and dimensional stability.