Key points for custom injection molding of PP spoons

Key Points for Custom PP Spoon Injection Molding

Phase 1: Design and Materials - Balancing Function and Efficiency

Spoon Structural Design:

Wall Thickness: This is crucial. Typically controlled between 1.0 and 1.5 mm. Too thick and it shrinks easily; too thin and it's difficult to fill and lacks strength. A smooth transition is essential.

Draft Angle: Sufficient draft angle (usually 1.5° - 2°) is necessary because the spoon is deep; insufficient angle can lead to demolding difficulties, surface scratches, and even mold damage.

Edge Treatment: The spoon rim should have slightly rounded corners to avoid sharp cuts and improve plastic flow.

Stacking Design: If stacking for packaging is required to save space, the handle or body should have precise stacking clips or guide structures.

Material Selection and Processing:

Advantages of PP Material: Food-grade PP is the absolute first choice due to its non-toxicity, odorless nature, FDA compliance, low cost, and good toughness.

Additives:

Masterbatch: To provide the desired color, food-grade masterbatch must be used.

Slip Agent: Reduces friction between spoons, facilitating automated packaging and handling.

Material Pretreatment: PP has low water absorption, but to ensure optimal quality, it is recommended to dry at 80℃ for 1-2 hours to remove trace surface moisture.

Second Stage: Mold Design - The Core of High-Speed Automation

The spoon mold is a prime example of an ultra-high cavity number, high hot runner mold.

Multi-Cavity Mold:

To pursue ultimate efficiency, the number of mold cavities is usually very high, such as 32, 64, 96, or even 128 cavities. The cavity layout needs to be rheologically calculated to ensure balanced filling.

Hot Runner System: Absolutely standard.

A needle valve type hot runner must be used. Advantages:

No Waste: No sprue (gate) is generated, saving every gram of raw material.

Fully Automated: Robotic arms can directly handle parts without subsequent separation.

Aesthetically Pleasing Gate: Minimal traces at the valve needle closure, not affecting use.

Venting System:

Precision venting grooves (approximately 0.02mm deep) must be created at the end of the cavity (e.g., the end of the spoon handle). Poor venting will lead to scorching (yellow streaks) or incomplete filling.

Cooling System:

The design must be efficient and uniform to match the extremely short production cycle. Uneven cooling will cause the spoon to deform.

Ejection System:

Ejector pins should be placed in non-critical areas such as the spoon handle and back to ensure smooth ejection without leaving obvious marks.

Third Stage: Injection Molding Process - Efficiency and Quality Control The goal is to achieve a "second-level" cycle time while ensuring product integrity.

Injection Molding Machine Selection: A machine suitable for high-speed injection molding, with fast injection speed and sensitive response.

Core Process:

Mold Temperature: 40-60℃. A suitable mold temperature facilitates demolding and ensures dimensional stability.

Injection Speed: High-speed injection. This allows the melt to quickly fill all cavities before cooling, preventing cold material buildup.

Holding Pressure and Time: Use lower holding pressure and shorter holding time. Because the spoon's walls are thin, excessive pressure can easily generate internal stress, leading to later deformation and wasted production time.

Cooling Time: Extremely short, only a few seconds. The entire production cycle can be controlled within 5-8 seconds.

Fourth Stage: Post-processing and Quality Inspection

Post-processing:

Fully Automated: Robotic arms automatically pick up parts and place them into a conveyor belt or collection box for direct packaging. No human contact, meeting food hygiene requirements.

No Gate Removal: Hot runner production eliminates this step.

Quality Inspection:

Appearance Inspection: Check for missing materials, burrs, burning, color differences, and contamination.

Dimensional Check: Use calipers to measure the spoon's total length, spoon head size, etc.

Functional Testing:

Drop Test: Samples are dropped freely from a certain height to test their toughness and whether they break.

Hand Feel and Stiffness Test: Manually bend the spoon to assess its rigidity and resilience.

"We are experts in high-efficiency, low-cost solutions":

"We use ultra-high cavity molds with 96 or more cavities and needle valve hot runners to minimize the production cost per spoon for you."

"Our optimized ultra-short cycle time process ensures an impressive daily production capacity, guaranteeing your supply needs."

"We have a complete system to ensure food hygiene and safety":

"We use 100% food-grade virgin materials and compliant color masterbatches, and provide relevant certifications (such as FDA test reports)."

"Our production workshop meets GMP standards, achieving clean production throughout the entire chain from raw materials to finished products."

"We offer flexible customization services":

"We can customize any color according to your brand requirements and etch your logo on the mold."

"We can design spoons of different capacities (e.g., 10ml, 15ml) and shapes (round head, oval head) to meet your specific application scenarios."