How To Repair A Broken Nipple On A Evap Line On A Plastic Gas Tank

Posted on: Nov.23th, 2018| Past Judy, WayKen Projection Director

The advantages of plastic injection molding for manufacturing parts methods include fast production speed, loftier efficiency, automation of performance, shapes, and size flexibility. Moreover, the injection molding products are authentic in size, easy to be replaced, and the mold parts can be formed into circuitous shapes. This eco-friendly method is suitable for the molding processing fields such as mass product and circuitous shape products.

Even so, although the operators are familiar with specific machines and the operational skills in the molding process of plastic parts, the various rapid injection molding defects on mold design and materials are inevitable. The article aims to plastic injection molding problems and solutions, mainly as follows:

Clarify the causes of these issues generated from raw materials, plastic parts or mold design, molding processes, etc., and suggest related solutions.

ane.Short Shots

Curt shots are a phenomenon in which the mold crenel cannot exist completely filled.

Causes: (1) Die temperature, cloth temperature or injection pressure and speed are as well low (ii)Uneven plasticization of raw materials (three)Poor exhaust (4) Insufficient liquidity of raw materials (5)The part is besides thin or the gate size is besides minor (half-dozen) Polymer cook is prematurely cured due to unreasonable structural design

Remedies: Textile: Use more fluid materialsMold design: (1) Fill the thick wall earlier filling the sparse wall to avert the retentivity miracle. (2) Appropriately increase the number of gates and runner size to reduce the process ratio and menses resistance (3) The position and size of the exhaust port should be properly prepare to avoid the miracle of poor frazzle.

Machine: (1）Check whether the check valve and the inner wall of the material cylinder are seriously worn (2) Check if the feeding port has material or whether it is bridged.

Process: (1) Increase injection pressure and injection speed to enhance shear heat (2) Increase the amount of injection (3) Increase material cylinder temperature and mold temperature

two. Air Traps

Air traps is that air is trapped in the crenel to create bubbles in the part.

Causes: It is caused past the air being unable to escape from the parting surface, the ram, or the vent when the two melt fronts meet.

Remedies: Structural design: Reduce thickness inconsistency and endeavor to ensure uniform wall thickness

Mold design: (i) Add a vent at the last filled identify (2) Redesign the gate and runner organization

Procedure: (1) Reduce the injection speed of the last stage (two) Increase the mold temperature

three. Brittleness

Brittleness is that the plastic function is hands cracked or broken in some place

Causes: (ane) Dry out conditions are not suitable; use excessive recycled materials (2)Injection temperature setting is wrong (3) The gate and runner system settings are not appropriate (4) The melting marker force is not high

Remedies: Material: (ane) Set appropriate drying conditions earlier injection molding (2) Reduce the use of recycled materials and increase the proportion of raw materials. (3) Use high-strength plastic. Mold design: Increment the size of the main runner, co-operative runner, and gate

Machine: Choose a well-designed screw to make the temperature distribution more uniform during plasticization

Process: (one) Reduce the temperature of the material cylinder and nozzle (ii) Reduce dorsum pressure, screw speed and injection speed (three) Increase the fabric temperature and injection pressure, improve the melting forcefulness

4.Fire Marks

The burn marks are that the gas in the crenel cannot exist removed in time, resulting in blackening at the cease of the menstruation.

Causes: (1)The air in the cavity cannot be removed in time. (2) Material deposition: overhigh melt temperature; clouded screw speed; improper design of the runner system

Remedies: Mold design: (one) Add an exhaust system to a place where the exhaust gas is easily generated (ii) Increase the size of the runner system

Process: (1) Reduce the injection pressure and speed (2) Reduce the barrel temperature (3) Check if the heater and thermocouple are working properly.

five.Flash

It ways that excess plastic is present on the mold parting or ejector part.

Causes: (1) Insufficient clamping force (2) The mold has defects (3) The molding weather condition are unreasonable (iv) Improper design of the frazzle arrangement

Remedies: Mold blueprint: (1)Reasonably design the mold to ensure that the mold can be airtight when the mold is airtight (2) Check the size of the exhaust port (three) Cleaning the mold surface

Motorcar: Set the machine of the appropriate size procedure: (1) Increment the injection time and reduce the injection speed (2)reduce the barrel temperature and nozzle temperature (3) Reduce the injection pressure and pressure

6.Delamination

It refers to the surface of the office that can be peeled off layer past layer.

Causes: (1) Mixing other incompatible polymers (2) Excessive release agent used during molding (three) resin temperature is inconsistent (iv) Excessive moisture (five) The gate and the flow path have sharp angles

Remedies: Material: Avoid incompatible impurities or contaminated recycled materials mixed into the raw materials Mold design: Chamfer all runners or gates with sharp angles

Process: (ane) Increase the butt and mold temperature (2) Appropriate drying of the material before molding (iii) Avert using too much release agent

7.Jetting

A spray trace caused past the melt flowing too fast, generally serpentine.

Causes: (i)The gate size is too small, and it is facing the product surface with a big cross-sectional area (2) Filling speed is too fast

Remedies: Mold design:(1) Increase the gate size (2)Change the side gate to the lap gate (3)Increase the finish pin in front end of the gate

8.Flow Lines

Flow lines are molding defects that are wavy on the surface of the production known as a kind of frog jump caused by the slow menstruum of the melt.

Causes: (1)Mold temperature and the textile temperature is as well low (2) Injection speed and pressure is besides slow(3) The size of flow channel and gate is too small (4) Due to the structure of the product, the dispatch is likewise large when the filling flow is caused.

Remedies: Mold blueprint: (1) Increase the size of the cold well in the menstruation channel (two) increase the size of the runners and gates (3)Shorten the size of the main channel or switch to the hot runner

Process:（1）Increment the injection speed （2） Increase injection pressure and pressure （three） extend the pressure level belongings time （4）Increase the mold temperature and cloth temperature

9.Fog

A cloud-like discoloration occurs near the gate. The reason is the cook fracture.

Causes: If the gate is also minor or the cavity at the mucilage is too sparse, the period charge per unit of the melt is large, the area of the pause is small, the shear charge per unit is large, and the shear stress is oftentimes increased so that the melt safety breaks and the fog shift occurs.

Remedies: Moldflow simulation. It is possible to predict the temperature, shear rate, and shear stress of the melt passing through the above narrow zone. Moldflow generally provides an upper limit for the temperature, shear rate, and shear stress of diverse plastic materials. Moldflow engineers can brand adjustments based on the analysis results to find the appropriate gate size and cavity wall thickness at the glue inlet to eliminate fog.

x.Streaks

Streaks are those in which h2o, air, or char is distributed in the management of flow along the surface of the role.

Causes: (i)The moisture content in the raw materials is too high (ii) Air is trapped in the raw material (iii) Polymer degradation: the textile is contaminated, barrel temperature is too high; insufficient injection volume

Remedies: Mold design: Bank check if the exhaust position is sufficient Process: (1) Cull the right injection molding machine and mold (2) When switching materials, clean the old materials completely from the butt (3) Amend the exhaust system (4)Reduce melt temperature, injection pressure or injection speed

eleven.Sink Marks

It is a phenomenon in which the surface of the role is concave at the wall thickness.

Causes: (1) Injection pressure or holding pressure level is too low (2)The holding time or cooling time is likewise brusque (three) Melt temperature or mold temperature is likewise high (4) Improper design of the structure of the parts

Remedies: Pattern: (ane) Corrugated surface on the surface where dents are easy to occur(2)Reduce the thick wall size of the workpiece, minimize the aspect ratio, and the adjacent wall thickness ratio should be controlled at 1.5~ii, and endeavour to make a smoothen transition. Redesign the thickness of the ribs, counterbore, and ribs. Their thickness is generally recommended every bit 40-lxxx% of the basic wall thickness.

Procedure: (1) Increase the injection pressure and force per unit area (ii) Increase the gate size or change the gate position

12.Weld Lines

The weld lines refer to the surface defect acquired past the two streams existence welded together.

Causes: If at that place are holes, inserts, or multi-gate injection molding methods in the fabricated parts or the wall thickness of the parts is uneven, weld lines may be generated.

Remedies: Material: Increase the fluidity of plastic melt Mold Blueprint: (i) Modify the position of the gate (two) Add a venting slot Process: (one) Increase the melt temperature (two) Reduce the amount of release agent

13.Warpage

The nigh difficult problem to solve in the blueprint and production of plastic parts is the warpage.

Causes: (i)Mold structure: pouring, cooling arrangement and ejection system (two) Product structure: plastic parts wall thickness changes, with curved or asymmetrical geometry, ribs and Boss column design is not reasonable (3)Production procedure: the plastic parts are not fully cooled, and the injection and pressure holding curves are unreasonable (four)Plastic materials: plastic materials have, no added fillers, the size of the shrinkage.

Remedies: (1)The mold temperature is unstable. Provide cooling/heating balanced mold (2)Irregular section thickness Redesigned production shape and size according to resin characteristics

At WayKen, we accept encountered many similar plastic injection molding bug and solutions in some cases of paradigm injection molding. In order to create injection molding products for our customers, nosotros extremely have injection molding machine parts details and injection molding pace past footstep to heart earlier manufacturing parts and during the injection molding process.

Source: https://waykenrm.com/blogs/plastic-injection-molding-problems-and-solutions/

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