工艺注塑手册 Injection process handbook(二）_【郴州市合创塑胶制品有限公司】

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一. 基本概念：

Basic conception:

1. 收缩：

Shrinkage:

（1）收缩的原因：.a.热胀冷缩；

.b.熔体结晶；(结晶度越高，熔体收缩越严重)

.c.分子取向；（一般来说，分子总是沿着流动方向取向的。对于未增强型材料，其熔体在流动方向上的收缩总是大于垂直方向；对于增强型材料，正好相反）

. d.状态变化

The reasons of shrinkage: a. Chang from hot to cold;

b. Crystallization ;( The more crystallization, the more shrinkage)

c. Molecule orientation;

(For non-strengthen material, the shrinkage in the flowing direction is more than that, which is vertical with the flowing direction; and for the strengthen material, the result is just reverse,)

d. Form changing

（2）收缩的阶段：

The stages of shrinkage:

收缩从注射开始就随着熔体的逐步冷却而开始

The shrinkage starts from injection to forever.

它包括三个阶段：a.从注射开始到保压结束；b.从冷却时

间开始到脱模前；c.脱模后

It contains three stages: a. From injection stage to end of

holding stage;

b. From cooling stage to demold

stage;

c. After demold.

（3）变形：

Deformation

变形的根本原因时收缩的不均匀。造成收缩不均匀的原因有：

The root cause of deformation is inhomogeneous shrinkage. The causes of

inhomogeneous shrinkage are as follows:

a. 冷却(即温度分布)不均匀

Inhomogeneous cooling

b. 壁厚不均匀

Different wall thickness

c. 压力分布不均匀

Not average location of pressure location

d. 分子取向

Molecule orientation

e. 脱模受力不均

Inhomogeneous forces when demolding

2. 结晶

Crystallization:

（1）什么是结晶：

What is crystallization:

简单的说，结晶就是指分子的有序排列

In a short word, it means to make the molecule in order.

（2）结晶的影响因素：

Factors affecting crystallization:

结晶的影响因素：冷却速度。冷却速度越快，结晶程度越低。

The cooling speed affects the crystallization. The faster cooling speed the more crystallization

（3）结晶对产品性能的影响：

How does crystallization affect the parts:

结晶度越高：密度越高

收缩越大

光洁度越好

强度越高

韧性变差

The more crystallization: The higher density

The more shrinkage

The better surface

The stronger of the parts

3. 粘度：

（1）什么是粘度：

What is viscosity:

粘度是流体本身的一种性能，它的大小是流体流动性能的一种衡量。数值越大，流体的流动性能越差。

Viscosity is a character of the flowing material. Its value is used to measure the flowing character. The bigger value it is, the worse flowing character it is.

（2）粘度的影响因素：

What affect the viscosity:

a.温度

Temperature

b.剪切速度

Shear rate

c.压力

Pressure

千万注意：往往粘度是三者共同作用的结果。不同的材料对温度，剪切速度和压力的敏感程度是不同的，并且在不同的注射速度下哪一个起主导作用也是不同的

    Attention: The three factors affect the viscosity together all the time. Different material are differently sensitive to temperature, shear rate and pressure, and which factor will be the main factor in different phase is also different.

通常：（A）对温度敏感：PA；PC

      Normally:       Sensitive to temperature: PA, PC

对剪切速度敏感：POM；PP；PE

                              Sensitive to shear rate: POM, PP, PE

对压力敏感：PP；PE

                            Sensitive to pressure: PP, PE

( B ) 在高速注射的情况下，剪切速度起主导作用(所以,对于薄壁

      产品或含薄壁部分的产品宜采用高速注射)。

In high injection speed situation, the shear rate is the main factor. (So use high injection speed for thin wall thickness parts)

4. 止回阀:

Non-return valve:

a. 止回阀的功能是什么:

Function of non-return valve:

在注射，保压时防止熔体倒流，从而给予熔体我们所需的压力和速度。

To prevent the melt flowing back when injection and packing.

b. 怎么判断止回阀或料筒损坏

How to recognize the non-return valve is broken:

初步判断：经常性的出现料垫不稳，或无料垫。

Recognize presumedly: Melt cushion is not stable usually or no cushion.

准确判断：延长保压时间，如果出现零料垫则说明止回阀损坏或料筒损坏。

Recognize precisely: Prolong the holding time, if there is no melt cushion, the non-return valve is broken or the cylinder is broken.

c. 怎么区别止回阀损坏还是料筒损坏

How to recognize the non-return valve is broken or the cylinder is broken:

方法一：换上新的止回阀，延长保压时间依然没有料垫，则说明料筒损坏。

Method 1: Change into a new non-return valve; prolong the holding time, if there is still no melt cushion, it means the cylinder is broken.

方法二：放大料垫，延长保压时间依然没有料垫，则说明止回阀损坏；反之则说明料筒损坏。

Method 2: Make the melt cushion big enough; prolong the holding time. If there is still no melt cushion, it means the non-return valve is broken; if there is melt cushion, it means the cylinder is broken.

未完待续