Custom Plastic Injection Molding Manufacturer and Factory

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Table of content

A) Does not affect the application of the product to the end user.

B) Does not interfere with post-process or customer assembly and processing.

C) Does not affect aesthetics.

D) Reliability

A) Purpose: to make the injection molded components meet the design and customer requirements and prevent batch scrap.

B) The first inspection time is before each production batch, after material change, after exception handling(mold repair, insert changed, ejector pin changed).

C) Note for the first inspection:
Before sending the first inspection, the workshop technician must do a good self-inspection:
check whether the product matches the drawings and other requirements, especially pay attention to structural issues; color matching; no obvious injection defects in appearance; Check assembly and functionality (especially new products, mold repaired, insert changed, ejector pin changed, injection parameters changed).

A) Purpose: timely detection of abnormalities in the injection modling process to prevent batch scrapping.

B) The inspection time is 3 shots per each machines per each two hours.

C) Note for the in-process quality inspection:
Support operation and production trouble shooting solution in many ways, such as machine, material, operator, method, management factors, to identify abnormalities, analysis of abnormalities, to solve abnormalities

A) Inspection timing: the injection modling workshop has produced finished products, placed them in the area to be inspected, and the operator informed the quality inspection guys.

B) Sampling standards: Sampling according to customer requirements; sampling according to enterprise specifications if customers do not require.

C) Inspection includes labeling, material, appearance, size, assimilability, and packaging etc.

A) room temperature 20℃±2, humidity between 30%~80% (no condensation).

B) Place the product under 40W fluorescent lamp or 60W ordinary light bulb 0.8~1m position, in 45°~135° direction, both eyes 30~45cm from the product,The visible face stays 3~5s, and the other face 2~3s.

Ⅰ: Products refer to products that do not require painting, such as DVR, wall box cover, satellite switch glue tray, PHLIPS antenna and other products for indoor use with high surface requirements;

Ⅱ: Products refer to products that require painting and outdoor products.

A-Surface:The part that is visible during normal product operation, such as the top cover, front end and interface area.

B-Surface:The surface that is not often visible in normal product operation, such as the side of the product.

C-Surface:Tthe surface that is not visible in normal operation, such as the bottom of the product.

D-Surface:The non-exposed surface of the product structure, such as the inner surface of the product and the internal structural components.

Fatal defects (Grade A)
Defects that can cause harm or be unsafe to the product user.

One or more fatal defects are called fatal non-conforming products; such products should be strictly limited (not allowed to leave the factory) to eliminate the defect. If the user finds a fatal defective product, you can reject the (batch) of products.

Due to fatal defects caused by user losses and hazards, injection molding factory will not only lose their reputation and cause great economic losses but also bear legal responsibility.

Serious defects (B level)
Although it will not constitute the same consequences as fatal defects, it will not cause harm to the user. Still, it can cause failure or seriously reduce the product’s performance, greatly reducing its expected function.

One or more serious defects, not including fatal defects in the product, is called a serious non-conformity.

Minor defects (Class C)
Only a slight impact on the application of the product performance or almost does not constitute a defect.

One or more minor defects without fatal defects and serious defects of the product are called minor non-conforming products.

There are also quality defects according to the severity of the four levels: fatal, serious, general, and minor.

Material defect:
Wrong material, mixed material, unconfirmed large proportion of Sprue material (Serious defect).

Minor appearance defects:
Scratches, shrinkage, material flow mark, color difference, ejector mark etc on the B and C surfaces of Ⅰ level products and A, B and C surfaces of Ⅱ level products.

Serious appearance defects:
Scratches, shrinkage, material flow mark, color difference, ejector mark, welding line that affects assembly etc on the A surfaces of Ⅰlevel products and Ⅱ level products.

Product construction (assembly) defect:
Resulting in product not being assembled or failure to achieve the expected function,For example: serious misalignment of the upper and lower covers after assembly, mismatch of the screw teeth, cracking after locking the screw,etc.

Product performance defects:
Defects that cause the product failed to meet the expected function of the design. For example: paint peeling, plating plating off, steel hardness, strength failure, electrical connection breakage, short circuit, attenuation reflection is not up to standard, etc.

Packaging defects:
May cause the product to appear scratches or not implemented according to the requirements of the corresponding packaging materials protective film, plastic bags etc.

A) During the molding process of injection molded parts, we inspect the products and control the production with the concept of “zero defect”, and help the molding workshop to analyze the root causes of each defects.

B) If there are minor defects in the appearance of the produced injection molded parts, but the customer agrees to accept them and they do not affect the assembly, we can say OK.

C) Defective products causing poor assembly (hole cracking, difficult to locking screw, scorching, deformation affecting assembly, large joints, fracture, fastening is not tight, misalignment etc) shall be rejected.

Surface appearance:
●Surface without burrs, welding lines, bubbles, flow marks, deformation, scratches.
●No Color difference (pay attention to the check assembled parts).
●No any marks/issues at gate position.
●No Flash around parting lines, insert lines.

Product structure:
●No plugging, hole (big or small), deformation, whitening, welding line at screw hole position.
●There should be no cracks or fractures in the joints.
●Go NO GO thread gauge required, pin gauge required.

Test assembly, functional and spraying.

2.1 Close the main power switch of the injection molding machine, check whether the equipment is electric leakage, preheat the barrel and mold according to the set process temperature, and keep warm for more than 20min when the barrel temperature reaches the process temperature to ensure the uniform temperature at the whole barrel.

2.2 Open the oil cooler to cool the water valve, returned oil and water pipeline, and start up the oil pump, if no abnormalities are found, then official start of the oil pump; wait until the screen shows “motor on” before starting to rotate, pay attention to the motor reversal, check whether the role of the safety door is normal.

2.3 Manually start the screw rotation and check the sound of the screw rotation is not abnormal and jammed.

2.4 The operator must check whether the safety door is normal. If the safety door travel switch is not working, it is forbidden to start the machine, and it is strictly forbidden to operate without using the safety door (cover) (emphasize to the staff).

2.5 The operating equipment’s electrical, hydraulic, and rotating parts should be covered and fixed with various covers and guards.

2.6 No one is allowed to press the buttons and handles without permission, and no two or more people are allowed to operate the same injection molding machine simultaneously.

2.7 Place the mold and insert to be stable and reliable. Stop immediately if any abnormality is found in closing the mold, and inform the technical personnel to troubleshoot.

2.8 When repairing the machine or cleaning the mold for a longer period (more than 10min), make sure to back off the injection barrel so that the nozzle leaves the mold and turn off the motor; The operator is not allowed to leave work while the maintenance personnel are repairing the machine.

2.9 No one is allowed to start the motor when someone is handling the machine or mold.

2.10 The power must be cut off when the body enters the machine or when the mold is open.

2.11 Avoid hitting the mold with the injection seat when the mold is open to prevent the mold from falling off.

2.12 Generally, each injection should not exceed 5s When inject it outwards. If the injection does not work twice in a row, pay attention to informing the neighboring personnel to avoid the danger zone.
When cleaning the injection nozzle, do not allow direct hand cleaning, using iron pliers or other tools to avoid burns.

2.13 The barrel has high temperature, high pressure and high electric power in the working process, it is forbidden to step on the barrel, climb and put objects on the barrel to prevent burns, electric shock and fire accidents.

2.14 In case the hopper is not fed, do not use metal bars or rods to stab the hopper roughly to avoid damaging the screen, screen guard and magnet frame inside the hopper, which will easily cause serious damage to the equipment if the metal bars are caught in the barrel when the screw is rotating.

2.15 If the machine is found to have abnormal sound, odor, sparks, oil leakage and other abnormalities in operation, it should be stopped immediately and reported to the relevant personnel of injection molding factory, explaining the fault phenomenon and possible causes.

The injection molding manufacturer should teach the staff to strictly comply with the above matters to ensure safe production and smooth production, so as to ensure quality and quantity delivery to customers

To strictly control the black spots on the surface of moulded plastic parts, improve the quality of moulded products, reduce the waste of raw materials and labor, and reduce costs, our plastic injeciton molding factory can develop preventive measures in our injection molding factory as follows:

We apply these experiences to automotive, medical, electronic, white household appliances etc industry,

3.1 The injection molding manufacturer should thoroughly clean the residual material or dust in the grinder or mixer before grinding or mixing the material.

3.2 When the plastic injection molding factory is playing material, if there is a contaminated or black spot on sprue material or scrap products, it must be picked out (such as: clean oil, air gun blowing off dust, etc.) before grinding. It is strictly prohibited to grind the wrong material or mixed material.

3.3 After all the materials are ground or mixed and put into the material bag, the injection molding factory must seal the material bag in time and mark it well.

3.4 All the plastic bags or tools for material must be cleaned thoroughly by the injection molding factory.

3.5 The injection molding manufacturer should keep the material grinding and mixing place clean and dust-free, the mixing machine should be covered at any time, and the material at the material gate should be cleaned in time and the material gate should be closed.

3.6 The baking barrel must be cleaned, the air inlet should be wrapped with dustproof cloth to prevent dust from entering the baking barrel.

3.7 The injection molding factory needs to clean the dust outside and bottom of the material bag before feeding material,If there is raw material left in the bag after feeding, the bag should be sealed in time.

3.8 Injection molding plant’s hopper material is not allowed to add too full, and should always cover the hopper cover tightly to prevent the dust in the air fall into the hopper.

3.9 Clean the foreign matter and dust in the sprue box before loading sprue material or waste products.

3.10 When opening the mold and adjusting the machine in the injection molding factory, it is strictly forbidden to use dirty hands to get the product and the sprue, the injection molding factory must put on clean gloves or wash your hands before getting them.

3.11 Products and sprues with oil or black spots must be placed separately from clean scrap or sprues, and the injection molding manufacturer must pay attention to the fact that they are not mixed together.

3.12 All the bad products (including sprue material) which are contaminated or have many black spots must be treated as black material or scrap, and the black spots in the larger plastic parts should be picked out with a knife before putting them into the spouting plastic barrel.

3.13 When the sprue material or scrap (including products) falls on the ground, it should be picked up and wiped clean (or blown clean) in time, and it is strictly forbidden for anyone to throw the contaminated (black spot) sprue material or products into the clean sprue rubber bucket.

3.14 When the sprue or scrap parts are full of a basket/bucket, it should be ground into sprue material in time, when it is too late to grind, it should be covered with a plastic film bag.

3.15 Do a good job to clean the machine and wash the bubble when the machine is on/off, to prevent the raw material in the barrel from charring due to high material temperature or too long time of heat.

Usually transparent or white injection molded parts require a high level of management for the injection molding company, because any small detail failure will result in the production of products with black spots or impurities that do not meet the requirements.

We have more than 20 years of plastic injection molding factory experience, and we have very rich experience in this kind of high requirements of transparent or white injection molded parts, and we can provide you with transparent or white injection molded parts very well at our precision plastic injeciton molding factory.