工艺注塑手册 Injection process handbook(三）

技术交流...



三.基本参数：

    Basic parameters:

1. 注射速度：

Injection speed:

（1）什么是注射速度：

What is injection speed:

通常我们所设定的注射速度是指螺杆前进的速度。但是真正重要的是

熔体在型腔里前进的速度，它与流动方向的截面积大小有关。

The injection speed, which we can set on the machine, is the screw forward

speed. But what is very important is the melt forward speed in cavities

（2）怎么确定注射速度：

How to set the injection speed:

作为原则，注射速度应越快越好。

As a rule, the injection speed should be the faster the better.

它的确定取决于熔体的冷却速度和熔体粘度：

 冷却速度快的或粘度高的熔体采用高的注射速度。

注意：冷却速度的快慢取决于材料本身的性能，壁厚以及模具温度高低。

The injection speed is determined by the cooling speed and the viscosity of melt:

 

 

 

To the melt, which cooling speed is very fast and the viscosity is high, we ‘d better use fast injection speed. Attention that the cooling speed is determined by the material character itself, wall thickness and mold temperature

（3）注射速度太快：易出现焦斑，飞边，内部气泡或造成熔体喷射

Too fast injection speed: burns, flash, air bubble inside or melt jet.

注射速度太慢：易出现流动痕， 熔接痕，并且造成表面粗糙，无光泽

Too slow injection speed: Flow line; weld line, or bad surface.

* 注射速度和注射时间设定的一般原则:

   General principles when setting injection speed or injection time:

 

2. 转压点：

Switch point:

（1）怎么确定转压点：

How to set switch point:

一般来说，转压点是指在零保压压力的情况下把产品打到95％满时，

由注射到保压的切换点。

Normally the switch is the changing point of screw from injection phase to

holding phase, when the parts are 95% of their volume.

对于薄壁产品（如：扎带）：一般打到产品的98％

To the thin wall thickness parts (Example: Cable strap): Up to 98% of their

volume.

对于非平衡流道：一般为70％-80％，应视具体情况而定。并建议采

用慢-快-慢多级注射。

To non-balance runners: Normally it’s up to 70% to 80%. It should be

determined by the reality. We suggest using step injection speed (Slow- Fast- Slow).

（2）转压点太高：产品充模不足，熔接痕，凹陷，尺寸偏小等

Too high switch point: empty part, weld line, sink mark, and small

dimension

转压点太低：飞边，脱模困难,尺寸偏大等

Too low switch: flash, difficult to demold， big dimension.

3. 保压压力：

Holding pressure:

（1）怎么确定保压压力：

How to set the holding pressure:

优化的保压压力一般为最低保压压力和最高保压压力的中间值。

The optimized holding pressure is in the middle of the maximum and

minimum normally.

最低保压压力：在准确的转压点基础上，给予一定的保压压力，当产品刚出现充模不足时的保压压力。

Minimum holding pressure: based on the correct switch point, the pressure

when the parts start to be empty .

最高保压压力：在准确的转压点基础上，给予一定的保压压力，当产

品刚出 现毛刺时的保压压力。

Minimum holding pressure: based on the correct switch point, the pressure

when the parts start to have flash.

（从最低和最高保压压力我们可以看到产品工艺波动的安全范围）

(From the maximum holding pressure and minimum holding pressure, we can see

the safe extension of the parts when the process is a little bit fluctuate)

 

（2）一般来说：

Normally:

PA保压压力=50% 注射压力

POM 保压压力= 80% 注射压力；对于尺寸要求高的产品可达到

100％注射压力

PP/PE 保压压力=30-50％ 注射压力

PA Holding pressure = 50% Injection pressure

POM Holding pressure = 80% Injection pressure; 100% Injection

pressure to high dimension requirement parts

PP / PE Holding pressure = 30-50% injection pressure

4. 保压时间：

Holding time:

（1）怎么确定保压时间：

How to set holding time:

保压时间的确定以浇口冷凝为依据。通过产品称重来确定。

Holding time is determined by the solidification time of the gate. We decide

it according to the weight.

（2）保压时间太长： 影响周期

Too long holding time: Waste time

保压时间太短：重量不足，产品内部空洞，尺寸偏小

Too short holding time: Not enough weight, empty inside, small dimension

*  注意：保压压力会影响保压时间的长短。保压压力越大保压时间越长。

Attention: The holding pressure will affects the holding time. The higher holding  

pressure the longer holding time.

5. 螺杆转速

Rotation Speed:

预塑的目标是：获得均一稳定的熔体（即塑化均匀，无冷料，无降解，无过  

                           多气体）

Target of plastification: To get homogeneous melt.

（1）怎么确定螺杆转速：

How to set the rotation speed:

作为原则，螺杆转速的确定必须使螺杆的预塑时间，回吸时间与射台

的回退时间之和略短于冷却时间。

As a rule, the rotation speed is determined by that the total dosing time, retract of screw and retract of injection unit must be a little bit shorter than the cooling time.

（2）螺杆转速太快：塑化不均（从而造成产品冷料，充模不足和断裂

等），材料分解（从而造成焦斑，色差，断裂等）

Too fast rotation speed: Inhomogeneous melt (which cause empty parts, broken), material decomposed (which cause burns, different color, broken etc)

螺杆转速太慢：影响周期

Too slow rotation speed: Waste time.

6. 冷却时间：

Cooling time:

作为原则，冷却时间的设定应越短越好，以产品不变形，不粘模，无过深的顶出痕为基本要求。并且：螺杆转速： PA

    关注 郴州市合创塑胶制品有限公司