The blow molding process requires constant adjustment. The purpose of these adjustments is to ensure that the product meets the requirements of small wall thickness while maintaining as uniform a wall thickness as possible. This approach helps reduce material consumption and achieves a high cost-performance ratio in terms of input and output. Today, our editor will introduce some key considerations for blow molding processing?

Points to note for blow molding processing:

1. Utilize the established computer model to simulate the conditions of blow molding molds, feeding parisons, clamping plates, etc.

2. Input the parameters that affect the parison wall thickness distribution in each stage.

3. Analyze the obtained simulation results, and reveal through computer simulation which parts have wall thicknesses that fail to meet the requirements, and which parts have excessive wall thicknesses.

4. Utilize artificial intelligence, adjust the input parameters, and repeat the processes of ① to ③ to ensure that the wall thickness of each part of the product is minimized as much as possible while achieving the minimum wall thickness.

5. Analyze and compare the outcomes of multiple process plans to ultimately determine the optimized process parameters. Stretch blow molding, also known as biaxial orientation blow molding, involves mechanically stretching the parison in the axial direction and inflating (stretching) it radially with compressed air to form packaging containers under the high elasticity of the polymer. Stretch blow molding can be performed in one step or two steps.

What issues should be considered in blow molding processing? The editor mentioned above has provided a brief introduction on this topic, hoping to be of some help to you. If you wish to know more, you can read other articles on this website. If you have any needs related to blow molding processing, you can contact us online, and we will be happy to serve you!

In the plastics industry, many companies, in order to save costs, often consider using blow molding as a manufacturing process for hollow products. Compared to injection molding, this method significantly reduces costs, which is why blow molding has experienced rapid development. However, in practice, the effectiveness of blow molding is often influenced by various factors. Next, the editor from Kunshan Juxinchang Company will summarize these factors for you.

The range of products processed by blow molding is very extensive, such as in the toy industry, packaging industry, electrical appliance industry, and other industries. Factors involved in the blow molding process, such as the position of the mold split (parting line), product slope, product layout, blow ratio, fillets, and appearance decoration, are considerations for mold engineers and blow molding engineers.

1、The position of the parting line: Before mold opening, the mold engineer needs to carefully consider how to part the mold, as this will affect the subsequent demolding of the product and its appearance.

2、The slope of the product: All surfaces parallel to the direction of mold movement should have a certain slope, which should be suitable for easy mold opening and convenient product removal. 

3、Check all functionalities: When used as a product, the fewer components and assembly work, the better, as it can reduce product costs. 

4、Blow molding ratio: During blow molding, pay attention to areas with very thin geometric shapes that may cause bulges or indentations. When the ratio of width to depth is too large, vacuum forming can be used as an auxiliary method. 

5、Radius principle: Avoid sharp edges, corners, sudden changes in surface, and sudden transitions in product diameter or wall thickness. 

6、The position of other inserts, vent slots, air intake needles, ejector pins, lettering, and labels should be carefully considered.

In summary, whether it's a small or large blow molding product, the effort and time required before development cannot be reduced. The editor from Kunshan Juxinchang Company reminds everyone to carefully consider the factors that may affect the blow molding processing effect, so as to ensure that every blow molding product matches both appearance and function well.

1. Key points of process control for blow molding in Suzhou

1) For extrusion blow molding

Pay attention to controlling the sagging phenomenon and wrinkling defects of the billet. If the vertical extension is too long, the wall thickness will decrease and the amount of residual material removed will also increase; If the vertical extension is not enough and the billet is too short, it cannot be inflated.

2) Wrinkling phenomenon

When the billet descends to a certain length, circumferential stress occurs due to the inability of the upper melt of the billet to bear its own weight; Generally, high melt strength, small expansion of billet diameter, high extrusion rate, and larger die gap all contribute to improving wrinkles.

3) Uneven wall thickness

Another issue is that when the billet descends, the wall thickness is uneven. Usually, a hexagonal nut is installed on the die of the machine head to adjust the gap between the core rod and the die.

4) Make sure to exhaust properly

To achieve good surface quality of the parts, attention must be paid to exhaust. For example, PE material is sandblasted on the surface of the mold with a particle size of less than 180 #, while blow molds made of hard plastic have exhaust holes, exhaust needles, and exhaust grooves; In addition, increasing the inflation pressure can also help improve the appearance of the product.

2. Defect elimination in Suzhou blow molding processing

1) Wrinkles

Check if the head die and core rod are coaxial

Reduce the temperature of the billet

Increase the die gap or molding section length of the machine head

Choose polymers with smaller expansion of the preform

2) Uneven length

Check for bridging of raw materials in the feeding hopper

Check if the temperature in the feeding section of the barrel is too high

Check for fluctuations in screw speed

Increase the back pressure of the extruder

Check the temperature control device of the extruder and head

Check for wear on the screw and barrel

Check if the recycled and new materials are mixed evenly

Check if the filter screen is cracked or partially blocked by magazines

3) Bubble hole

Strictly dry hygroscopic polymers

Heat the raw materials in the hopper to remove moisture

Reduce the water cooling capacity at the inlet of the extruder

Check and remove impurities from the raw materials

Clear the material accumulation inside the extruder and head, avoid explanation

Increase the back pressure of the extruder

4) Stripes

Remove impurities from raw materials

Remove impurities accumulated inside the machine head

Avoid material accumulation and explanation

Reduce the temperature of the billet

Polish or replace the die of the machine head

Replace the burnt heating coil

5) Gel

Screen out the fines from the recycled materials

Dry raw materials

Improve the dispersion and mixing performance of the screw and reduce the barrel size

In the entire process of blow molding products in Shanghai, many technical difficulties are encountered. Below, the editor of Kunshan Juxinchang Company will discuss with everyone the reasons for this problem and the corresponding solutions. We look forward to providing some opinions and suggestions for everyone to solve the difficulties.

1、 Uneven vertical wall thickness of finished products during blow molding processing in Shanghai

Causes:

① The weight sag of the billet is quite severe

② The diameter difference between the two vertical sections of blow molded products is too large

Solution:

① Reduce the temperature of the preform melt, increase the extrusion rate of the preform, adjust the use of epoxy resin with lower melt flow rate, and adjust the preform control equipment

② Moderately modify the product design plan and use bottom blowing method for forming

2、 Uneven horizontal wall thickness of finished products during blow molding processing in Shanghai

Causes:

① Billet extrusion tilting

② There is a significant temperature difference between the top block and the mold core inside and outside

③ Asymmetric product appearance design

④ The blowing ratio of the billet is too high

Solution:

① Adjust the gap width deviation of the mouth mold to make the wall thickness of the billet uniform; Before closing the mold, straighten out the broken shape

② Raise or decrease the heating temperature of the mold sleeve to improve the temperature error inside and outside the mouth mold

③ Before closing the mold, pre clamp and pre expand the billet to moderately offset it towards the thick walled direction

④ Reduce the blowing ratio of the billet

3、 When blow molding products in Shanghai, orange peel like patterns or black spots appear on the surface of the finished product

Causes:

① Poor exhaust of the mold

② Plastic mold water seepage or condensation in plastic mold concave mold

③ Poor melting of the billet causes cracking of the melt

④ Inflatable air pressure

not enough

⑤ The inflation speed is relatively slow

⑥ The inflation ratio is very small

Solution:

① Plastic mold blanks undergo sandblasting treatment and are equipped with exhaust holes

② Repair plastic molds and adjust the cooling temperature of the plastic molds to above the dew point

③ Reduce the screw speed of the extruder and increase the heating temperature of the extruder

④ Raise the inflation pressure

⑤ Clean the compressed air channel and check if there is any air leakage in the blowing rod

⑥ Adjust the mold sleeve and core to improve the blowing ratio of the billet

There is no doubt that blow molding products in Shanghai will continue to encounter many other difficulties. If it is not easy to handle, you can consult the editor of Kunshan Juxinchang Company online.