First, the basic principle of injection molding:

After the use of plastic injection molding machine is heated to a certain temperature, can be melted into the nature of the liquid, the molten liquid with high pressure is injected into the closed mold cavity, after cooling and shaping, the top of the mold after the plastic body to give the desired product.

Second, the injection molding of four elements:

1. plastic mold injection molding machine 2. 3. 4. plastic materials molding conditions

Third, plastic mold

Most use two plate mold, three plate mold, there are also some bit analog lines with a slider.

The basic structure: 1. male mold (lower mold) male mold fixing plate, male mold auxiliary plate, ejector plate, the public template. 2. The master mold (the mold) parent template, the master mold fixing plate, into the ring, locating ring. 3. constant temperature system cooling. Stable (equilibrium) set the mold temperature.

Fourth, the injection molding machine

Mainly by plastics, injection device, clamping device and transmission agencies; electric drive motor, motor driven oil pump, oil pump oil, hydraulic drive pistons, piston driven machinery, generate action;

1, according to the injection can be divided into:

1. The horizontal injection molding machine vertical injection molding machine 2. 3. 4. multicolor angle type injection molding machine injection molding machine

2, according to the clamping can be divided into:

1. direct pressure injection molding machine 2. 3. crankshaft direct pressure injection molding machine, crank compound

3, according to the charging mode can be divided into:

1. One-way plunger-type injection molding machine 2. 3. reciprocating screw injection molding machine screw injection molding machine

4, injection molding machine four systems:

1. Injection System

a multi-Segments of stirring resistance and corrosion resistance.

b. rate of fire, injection, holding pressure, back pressure, screw speed segmented control.

c. stirring resistance, long life screw device.

d. feeding tube interchangeability, self-cleaning.

balance e. oil pump, the stability.

2. Clamping System

a. high-speed, high rigidity.

b. auto mold, die change.

c. Automatic lubrication system.

d. equilibrium, stability.

3. The hydraulic system

a. all electronic feedback control.

b. the action smooth, high stability, closed.

c. Quick, energy efficiency.

d. hydraulic oil cooling, since the filter system.

The electronic control system

a multi. segmented, with memories of the microcomputer control expandability.

b. closed-loop circuit loop.

c.SSR (proportional, integral, differential) temperature control.

d. Self-diagnosis alarm function.

e. automatic production quality control, record.

Currently, most plastics used are: PP ABS PBT PC PA PPS POM and so on.

1, PP polypropylene material :( polypropylene) currently used by most brands are:

China Sinopec Zhenhai Refining & Chemical Fiber Taiwan Singapore mytex Hyundai India SEETEC

Features: lighter weight, good mobility, colorless, tasteless and odorless, non-toxic, good gloss, heat resistance, tensile strength, good secondary processing performance, good chemical stability and insulation; plus...... low price, mainly applicable to woven toys. Crate. appliances. tubing. sheet metal.

Our products are mainly used in electrical enclosures, such as: motor cover after three pipe fan shroud around the sun, and so after a small shell;

General molding conditions: 1. Mold temperature: 20 degrees to 40 degrees 2. Drying conditions: 80 degrees for 1-2 hours or more. 3. The cylinder temperature: 170 degrees to 220 degrees 4. The heat distortion temperature: 80 degrees (1.8MPa, 12.7mm). 5. Softening point: above 135 degrees 6. mold shrinkage: 0.5% - 0.7% (3.3mm) 7. tensile yield strength: 20-30Mpa;

Commonly used methods are modified: toughening retardant antioxidant weather high gloss;

2, ABS material :( acrylonitrile butadiene styrene resin three yuan). (Acrylonitrile-butadiene-styrene copolymer)

Currently, most used brands are: Taiwan's Chi Mei Taiwan China Petrochemical Fiber BASF Korea LG (Ningbo LG) Korea Kumho Chemical Samsung

Good impact resistance, high strength and rigidity, low temperature resistance, heat resistance, high gloss, easy to color and secondary processing, surface treatment: characteristics. Primarily for automotive electrical. Appliances. Building profiles.

Our products are mainly used in electrical enclosures, such as: fans cold water dispenser Heater fan ventilation Yuba and other products around the shell support, etc;......

General molding conditions: 1. The mold temperature: 40 degrees to 60 degrees 2. Drying conditions: 80 degrees more than 2-4 hours.

3. The cylinder temperature: 190 degrees to 230 degrees 4. The heat distortion temperature: 80 degrees (1.8MPa, 12.7mm).

5. General backpressure: 8-15kg / sq mm. 6. Mold Shrinkage: 0.5% - 0.7% (3.3mm)

Commonly used methods are modified: toughening retardant weather alloys;

3, PBT material :( polybutylene terephthalate fat poly butylene terephthalate) Celanese

Currently, most brands do not use fixed commonly used international brands are: DuPont singular universal Polyplastics Formosa DSM and Bayer;

Features: high abrasion resistance and rigidity, chemical resistance, weather resistance, dimensional stability, good electrical insulation, enhanced to better performance. Hygroscopic, susceptible to thermal decomposition, primarily for automotive electrical. Appliance connector precision instruments and electronics.

Our products are mainly used in heat-resistant parts: the outlet of the heater PTC buildings stand etc;.

:( According to general molding conditions vary in different proportions and defibrillators) 1. mold temperature: 100 degrees to 140 degrees 4 hours: 40 degrees to 60 degrees 2. dry conditions. 3. The feed tube temperature: 240 degrees to 270 degrees 4. heat distortion temperature: 210 degrees to 230 degrees (1.8MPa, 12.7mm). 5. The mold shrinkage: 0.3% - 0.5% (3.2mm) 6. Thermal decomposition temperature: 280 degrees (260 degrees in the tube can stay six minutes, otherwise it will break down, deterioration).

Commonly used methods are modified: toughening retardant;

4, PC material (polycarbonate polycarbonate)

Currently, most brands do not use fixed commonly used international brands are: Mitsubishi Bayer singular light Teijin Dow Polyplastics etc;

Characteristics: maximum impact resistance strength, dimensional stability, heat above 130 degrees, with high gloss and transparency, transmission rate can reach about 90%, non-toxic. High processing temperatures, after molding have stress, moisture, do not wear, corrosion fatigue. Mainly applied to food containers. CD. Lenses. Appliances. Optical instruments.

Our products are mainly used for oil heater, such as: Oil radiator panel partially bake hanger electronic Youting transparent cover, etc;.

:( According to general molding conditions vary in different proportions and defibrillators) 1. Mold temperature: 80 degrees to 100 degrees 2. Drying conditions: 100 degrees to 120 degrees for more than 4 hours. 3. The cylinder temperature: 250 degrees to 300 degrees 4. Heat distortion temperature: 130 degrees; 5. The mold shrinkage: 0.5% -0.7%

The PC material flow with increasing temperature is higher due to the molding temperature regulating large proportion.

Commonly used methods are modified: Enhanced flame antioxidant weather etc;

5, PA material (polyamide polyamide), also known as nylon NYLON

Currently, most brands do not use fixed commonly used international brands are: DuPont Dow Polyplastics Mitsubishi DSM, BASF and Bayer;

Features: abrasion, fatigue resistance, high water absorption, (after high intensity enhancement) excellent dimensional stability, (which can be used for high-precision mechanical objects).Primarily for automotive. Motor. Equipment.Now SMT.IC precision electronic connectors and other gear.

:( Molding conditions depending on the structure of the fiber and processing different proportions vary) 1. Mold temperature: 80 degrees to 120 degrees 2. dry conditions: 120 degrees to 140 degrees for more than 4 hours. 3. The cylinder temperature: 260 to 310 degrees 4. Thermal deformation temperature: 235 degrees 5. The mold shrinkage: 0.1% - 0.5%

Device Requirements: a screw:. (L: D = 20: 1) Standard three sections, with a check ring screw. (Optional enclosed nozzle diameter of 3.0mm) 2. feeding tube should be corrosion resistant and wear-resistant alloys. 3. template both sides need to strengthen insulation panels, to avoid heat machine. 4. Use a circular feeding channel, male and female mold heat evenly. 5. inlet diameter of 0.3mm to 0.5mm pinhole sneaked feed.

6. Use 0.02mm-0.04mm depth, 0.5mm-1.0mm width of the exhaust hole, and the subsequent exhaust gas effectively.

Commonly used methods are modified: Enhanced high viscosity and other wear-resistant;

6, POM POM material :( polyformaldehyde)

Characteristics: high abrasion resistance, fatigue resistance, excellent dimensional stability, (which can be used to require mechanical abrasion dimensionally stable object.) There are serious glare of gas decomposition, should be used to pay attention to the exhaust.

Flame resistance is poor, not acid. Oil, surface treatment of the poor, to be applied to the car. Gear. Sprayers Precision Electronics.

General molding conditions:

1. Mold temperature: 60 degrees to 80 degrees

2. Drying conditions: 80 degrees to 100 degrees over 2 hours.

3. Tube Temperature: 170-210 degrees

The heat distortion temperature: 90 degrees;

5. The mold shrinkage: 0.5% -0.8%

6. Thermal decomposition temperature: 240 degrees (240 degrees in the feed tube can stay five minutes, otherwise it will break down, deterioration).

7, PPS PPS steel material :( poly phenylene sulfide)

Features: abrasion, fatigue resistance, high water absorption, high flame itself, excellent dimensional stability,

(Can be used for high-precision mechanical objects) enhanced to better performance, similar to the sound of metal.

Crystalline poor, poor mobility, poor toughness, can not color.

Perishable tooling and machinery, prone to flash.

Primarily for automotive. Motor. Equipment.Now SMT.IC precision electronic connectors and other gear.

Our products are mainly used in high heat parts, such as:

. The PTC Heater wiring rack bracket and so on;

General molding conditions: (depending on the structure of the fiber and processing different proportions vary)

1. Mold temperature: 100 degrees to 150 degrees

2. Drying conditions: 120-140 degrees four hours or more.

3. The feed tube temperature: 270 degrees to 330 degrees

The heat distortion temperature: 260 degrees (1.8MPa, 12.7mm).

5. The thermal decomposition temperature: 400 degrees (1.8MPa, 12.7mm).

6. Mold Shrinkage: 0.1% - 0.4% (3.3mm)

Device Requirements:

1. Screw: (L: D = 20: 1)

Standard three sections, with a non-return valve screw. (Optional closed nozzle, having a diameter of 3.0mm)

2. Use the feed tube to be corrosion-resistant double-alloy wear-resistant materials.

3. template both sides need to strengthen insulation panels, to avoid heat machine.

4. Use a circular feeding channel, male and female mold heat evenly.

5. inlet diameter of 0.3mm to 0.5mm pinhole sneaked feed.

6. Use 0.02mm-0.04mm depth, 0.5mm-1.0mm width of the exhaust hole, and the subsequent exhaust gas effectively.

7. mold cavity should be chrome or make the appropriate surface treatment, reduce production when gas corrosion.

 

Six, molding conditions

Molding conditions: speed, pressure, temperature, time, travel, number.

1. The injection pressure (primary pressure):

In injection molding the top of the pressure per unit area of the plastic screw applied;

P = cylinder diameter D0 / D1 * screw diameter hydraulic pressure;

2. The holding pressure (secondary pressure):

Cooling the molten material in the cavity, then you must apply some pressure to supplement its contracted part,

Increased density, then screw on the pressure exerted called plastic packing;

3. Clamping force: (tonnage)

The maximum clamping force clamping mechanism that can be applied to the mold;

F = K * P * A (K = 0.4 ~ 0.7, i.e., the pressure loss coefficient);

P: The maximum pump pressure;

A: Lock template area;

* When setting generally does not exceed 80-100kg / sq cm;

The injection volume:

Injecting a plastic injection molding cycle by weight of the mold;

5. Injection capacity: the number of grams cm3.

When an injection molding machine screw as a maximum injection stroke the maximum amount that can be emitted;

G = 3.14 / 4 * D2 * S * Density

D: screw diameter

S: screw stroke

* Production cycle of the injection volume should be less than or equal to 80% of the machine with a maximum injection amount;

6. Rate of fire:

Screw to move within the tube, the stroke of movement per unit time is called the rate of fire;

V = S / T * 100%

S: Screw in the feed tube of the trip;

T: screw injection time;

7. backpressure:

When feeding, in the opposite direction of the screw retrograde, applied pressure on the molten plastic;

Backpressure effects:

1. Increase the molten plastic kneading effect; 2. increase the melting temperature of the plastic;

3. Increase the density of the molten plastic; 4. promote uniform plastic colors;

5. The exhaust gas within the molten plastic;

8. Low Voltage Protection:

Refers to a protective device for mold resistance generated during clamping, which can make the minimum of damage to the mold when pressed against the foreign body, reducing die losses.

Its working principle is the distance from the mold clamping clamping pressure low to set a certain period of time, when the mold clamping encountered during the course of the foreign body. Plastic or due to insufficient lubrication within the set time is less than the high-pressure lock when the switching point, the machine will generate an alarm, and the mold is opened;

Seven, forming quality improvement Analysis:

One, not shot full (lack of material)

1. insufficient injection pressure; 2. packing insufficient pressure;

3. Injection insufficient time; 4. feeding (accumulator) is inadequate;

5. shoot material staging location is too small; 6. injection end position is too small;

7. The injection speed is not fast enough; 8. nozzle, tube temperature is not enough;

9. The mold temperature is not enough; 10. feedstock drying temperature, the lack of time;