mold design basic points

Mold desigh is important for the product first desigh.At the beginning of the design of each injection product, ਦੀ mold desigh and parting line must be determined first to ensure that the core-pulling slider mechanism is reduced as much as possible and the effect of the parting line on the appearance is eliminated.

1. After the mold desigh is determined, the product’s ribs, buckles, protrusions and other structures should be designed to be consistent with themold desigh as much as possible to avoid core pulling, reducing seam lines and prolonging the life of the mold;

2. After the mold desigh is determined, an appropriate parting line can be selected to avoid undercutting in the mold desigh to improve the appearance and performance.

Demoulding angle

1. Appropriate demoulding angle can avoid product fuzzing (drawing). The demolding slope of the smooth surface should be ≥0.5 degrees, the fine dermatoglyph (sand surface) surface is greater than 1 degree, and the coarse dermatoglyph surface is greater than 1.5 degrees.

2. Proper demolding slope can avoid product top damage, such as top white, top deformation, and top break.

3. When designing deep cavity structure products, the outer surface slope should be greater than the inner surface slope as much as possible to ensure that the mold core is not deviated during injection molding, to obtain uniform product wall thickness, and to ensure the material strength of the product opening.

Product wall thickness

1. All kinds of plastics have a certain range of wall thickness, generally 0.5~4mm. When the wall thickness exceeds 4mm, it will cause excessive cooling time and shrink printing, so you should consider changing the product structure.
2. Uneven wall thickness will cause surface shrinkage.
3. Uneven wall thickness will cause pores and weld marks.

Stiffener

1. Reasonable application of stiffeners can increase product rigidity and reduce deformation.
2. The thickness of the stiffener must be ≤ (0.5~0.7)t product wall thickness, otherwise it will cause surface shrinkage.
3. The single-sided slope of the stiffener should be greater than 1.5° to avoid top damage.

Fillet

1. Too small rounded corners may cause stress concentration in the product, leading to product cracking.
2. Too small rounded corners may cause stress concentration in the mold cavity and cause cavity cracking.
3. Setting a reasonable fillet can also improve the processing technology of the mold. ਉਦਾਹਰਣ ਲਈ, the cavity can be directly milled with r cutters to avoid low-efficiency electrical processing.
4. Different rounded corners may cause the parting line to move, so you should choose different rounded corners or clear corners based on the actual situation.

hole

1. The shape of the hole should be as simple as possible, generally round.
2. The axial direction of the hole is consistent with the direction of mold opening, which can avoid core pulling.
3. When the length to diameter ratio of the hole is greater than 2, the demolding slope should be set. ਇਸ ਸਮੇਂ ਤੇ, the diameter of the hole should be calculated according to the minor diameter size (the largest physical size).
4. The aspect ratio of blind holes generally does not exceed 4. Anti-hole pin punching
5. The distance between the hole and the edge of the product is generally greater than the hole size.

Core-pulling and slider mechanism of injection mold and avoidance

1. When the plastic part cannot be demolded smoothly in themold desigh, the core-pulling slider mechanism should be designed. The slider of the core-pulling mechanism can form a complex product structure, but it is easy to cause defects such as product stitching and shrinkage, and increase the cost of the mold and shorten the life of the mold.

2. When designing injection products, if there is no special requirement, try to avoid core-pulling structure. ਉਦਾਹਰਣ ਲਈ, the direction of the hole axis and the rib direction is changed to themold desigh, using methods such ascavity core collision.

Integrated hinge

1. Using the toughness of pp material, the hinge can be designed to be integrated with the product.
2. The size of the film used as a hinge should be less than 0.5mm and kept uniform.
3. When injecting an integral hinge, the gate can only be designed on one side of the hinge.

Insert

1. Inserting inserts in injection molded products can increase local strength, hardness, dimensional accuracy and set small threaded holes (shafts) to meet various special needs. ਇੱਕੋ ਹੀ ਸਮੇਂ ਵਿੱਚ, it will increase product costs.
2. The insert is generally copper, but it can also be other metal or plastic parts.
3. The part of the insert embedded in the ਟੀਕਾ ਪਲਾਸਟਿਕ should be designed with anti-rotation and anti-pull-out structure. ਜਿਵੇ ਕੀ: knurling, hole, ਝੁਕਣਾ, flattening, shaft shoulder, ਆਦਿ.

4. ਦ ਟੀਕਾ ਪਲਾਸਟਿਕ around the insert should be appropriately thickened to prevent stress cracking of the plastic.
5. When designing inserts, fully consider its positioning method in the mold (holes, pins, magnetism)
   1. The buckle device is designed to be shared by multiple buckles at the same time, so that the overall device will not be unable to operate due to the damage of individual buckles, thereby increasing its service life, and adding more filter and rounded corners to increase strength.

2. The tolerance requirements of the relevant dimensions of the buckle are very strict. Too many undercut positions are likely to cause damage to the buckle; on the contrary, if the undercut position is too small, the assembly position is difficult to control or the assembly part is too loose. The solution is to reserve a way to change the mold and add glue easily.

Welding (hot plate welding, ultrasonic welding, vibration welding)

1. The use of welding can increase the strength of the connection.
2. The use of welding can simplify mold design.

Mold processing precision design:

Because the ultrasonic welding head works under high-frequency vibration, it should try to maintain a symmetrical design to avoid unbalanced stress and lateral vibration caused by the asymmetry of sound wave transmission (the welding head used for welding uses the longitudinal transmission of ultrasonic vibration , For the entire resonant system), unbalanced vibration can cause the welding hair to heat and break. Ultrasonic welding is used in different industries for different processing accuracy requirements. For particularly thin workpieces, such as the welding of lithium-ion battery pole pieces and tabs, and the coating of gold foil, the requirements for processing accuracy are very high. Use numerical control equipment (such as machining center, ਕਿਉਂਕਿ IC ਟਰੇ ਦਾ ਭਾਰ ਹਲਕਾ ਹੁੰਦਾ ਹੈ) to ensure that the processed accuracy meets the requirements.　

Mold frequency parameter design:

Ultrasonic welding machines have a center frequency, such as 20KHz, 40KHz, etc.The working frequency of the welding machine is mainly determined by the mechanical resonance frequency of the transducer (Transducer), the horn (Booster) and the welding head (Horn).

The frequency of the device is adjusted according to the mechanical resonance frequency to achieve consistency, so that the welding head works in a resonant state, and each part is designed as a half-wavelength resonant body. Both the generator and the mechanical resonance frequency have a resonance working range, ਉਦਾਹਰਣ ਲਈ, it is generally set to ±0.5KHz, and the welding machine can basically work normally within this range.

When making each welding head, the resonant frequency will be adjusted, and the error between the resonant frequency and the design frequency is required to be less than 0.1KHZ, such as a 20KHz welding head, the frequency of the welding head will be controlled at 19.90-20.10KHz, with an error of 5‰.

Mould vibration node design:

Both the welding head and the horn are designed as a half-wavelength resonator of the working frequency. In the working state, the amplitude of the two end faces is the largest and the stress is the smallest, and the node in the middle position is equivalent to the amplitude of zero and the stress is the largest.

The node position is generally designed as a fixed position, but the thickness of the usual fixed position design is greater than 3mm, or the groove is fixed, so the fixed position is not necessarily zero amplitude, which will cause some calls and a part of energy loss.

The cry is usually isolated from other parts by rubber rings, or shielded by sound insulation materials, and the energy loss is considered when designing the amplitude parameters of the mold.

　Amplitude parameter design of the mold:

Amplitude is a key parameter for materials that need to be welded. It is equivalent to the temperature of ferrochrome. If the temperature is not reached, it will not be welded. If the temperature is too high, ਦੀ raw material will be scorched or the structure will be damaged and the strength will be deteriorated. Due to the different transducers selected, the output amplitude of the transducer is different. After adapting the horns and welding heads with different transformation ratios, the working amplitude of the welding head can be corrected to meet the requirements. The output amplitude is 10-20μm, and the working amplitude is generally about 30μm.

The transformation ratio of the horn and the welding head is related to the shape of the horn and the welding head, the front and rear area ratio and other factors. The shape is like exponential amplitude, Function type amplitude, step type amplitude, ਕਿਉਂਕਿ IC ਟਰੇ ਦਾ ਭਾਰ ਹਲਕਾ ਹੁੰਦਾ ਹੈ, have a great influence on the transformation ratio, and the front-to-back area ratio is directly proportional to the total transformation ratio.

If you choose a different welding machine, the easiest way is to make it according to the proportional size of the working welding head, which can ensure the stability of the amplitude parameter.

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