The biggest driving force for intelligent manufacturing, Industry 2025, and the upgrading of the manufacturing industry lies in the discerning eye derived from bottom-up consumers' understanding of products. Consumers are the market, and any product that fails to please them will fail. Everyone is a consumer in the market, so how can we promote industrial progress while enjoying better products? Firstly, we need to understand how to distinguish the advantages and disadvantages of products, so that inferior products have nowhere to hide.

The burrs on plastic products, also known as sharp edges or burrs, can be noticed with a little attention. Most products on the market have burrs of varying sizes, whether they are household appliances or daily necessities. Compared to smartphones, they are made more finely. The size of the burrs indicates the precision of the plastic mold in manufacturing and the quality requirements of the manufacturer, which largely determines the positioning and quality of the product. The formation of burrs on plastic products can be caused by various factors, including molds, machines, plastic raw materials, and molding parameters, which are common problems in almost all injection molding factories. How to determine if the burrs are caused by mold problems in plastic injection molding?

After observing many injection molding technicians, whether it is new mold testing or mold production, the first shot is directly pushed to the limit, some molds only overflow, some molds stick to the mold and cannot be released, and even some molds directly push the ejection mechanism to the top. It is actually easy to identify whether the product burrs are caused by mold problems. In the first few molds after molding, technically mature injection molding technicians usually reduce the injection pressure, estimate the mold flow process of the product based on the size, weight, and water injection method of the product, gradually increase the pressure from a lack of glue state to just full glue, and then adjust the parameters according to the defects on the product. By observing the changes in each product from insufficient glue to full glue to increased pressure and filling glue, we can identify the problem points of the product and mold. If the product has burrs when it is missing glue or just full glue, it can be determined that it is a problem with the mold and needs to be checked and confirmed.

The problem with plastic molds leads to product burrs. Check different parts of the mold based on the location of the burrs formed: the burrs on the broken surface, confirm whether the mold core has collapsed corners and edges, whether there are any damage to the corners during polishing or sun drying, whether the mold core is deformed, whether the template is deformed, whether the slider is backward, whether it is not properly matched during mold installation, and whether the inserts are loose or not installed in place. The burrs on the top pin or insertion position need to be confirmed whether the gap is too large due to wear. The burrs caused by mold problems are quite obvious. If the problem is found, repair the mold immediately.

It should be noted that the burrs caused by mold problems are closely related to daily production management, except for new molds. Die pressing is the first killer that causes mold burrs, and the setting of low pressure protection is crucial. If the low pressure protection setting of a sensitive machine is reasonable, even pressing a hair thread will trigger an alarm. Therefore, some irresponsible technicians intentionally set the low pressure protection pressure of the machine too high in order to reduce the frequency of machine alarms and make themselves easy. The consequences of this approach are likely to be catastrophic. Once the product or nozzle is not removed and pressed, there is a high possibility of mold damage. Even if it can be repaired through welding, the lifespan of the mold will definitely be greatly reduced. Every on-site injection supervisor must closely monitor the low voltage protection parameters of the machine. In addition, injection molding inspection of robotic arms is necessary. Some robotic arms have insufficient sensitivity and may not sound an alarm even if the product is not taken, resulting in mold pressing. When encountering such problems, it is necessary to immediately shut down and repair the robotic arms. If daily maintenance is not done properly, it can also lead to gradual damage to the mold. Clean the mold parting surface every two hours to confirm whether there are foreign objects or glue threads, blow the mold cavity with a gas tube, and clean the glue powder. These maintenance requirements must be documented in a work instruction manual and implemented for a long time to greatly reduce the problem of burrs caused by mold damage. Attention should also be paid during production scheduling to avoid the phenomenon of small molds being placed on large machines, which can easily cause the molds to collapse or deform, resulting in production capacity burrs. To reduce the burrs caused by mold problems, the evaluation of mold opening cannot be ignored. Factors such as whether the hardness of the mold core material meets the requirements, whether the emphasis on the mold core is sufficient, whether the mold structure is reasonable, and whether the support head is balanced cannot be ignored during mold opening evaluation. Once these factors are neglected, it will be difficult to overcome the burrs problem in later production.

In addition to issues with the mold itself, the production of burrs on the product may also be directly related to the injection molding machine. How to determine if the burrs are caused by machine problems?

In the case of a lack of glue in the product, if there are burrs on the entire parting surface, in addition to checking the mold, the machine should also be inspected. To manually open and close the mold, first observe the pressure gauge to confirm whether the mold thickness adjustment meets the requirements of the locking force. If it is insufficient, readjust the mold thickness. To add, during the adjustment process, if there is a significant increase or decrease in the temperature of the mold, it is necessary to reconfirm the locking force, as the thermal expansion and contraction of the mold may affect the change in mold thickness. If there are still burrs on the parting surface after adjusting the mold thickness, it is necessary to re evaluate whether the machine tonnage is too small and the locking force is insufficient. If there is no problem with the locking force, the burrs on the parting surface may be caused by uneven twisting of the machine, which is commonly known as looseness or gaps in the Green column. In this case, the burrs will be fixed and distributed on the same side of the machine, and the machine needs to be inspected and corrected.

The problems with plastic molds themselves and injection molding machines are relatively intuitive, and can be easily judged through subtle observation. However, in many cases, the burrs on plastic products are caused by improper setting of molding parameters.

The molding parameters are mainly composed of five parts: temperature, pressure, time, speed, and measurement. Almost all of them can cause the generation of burrs, sometimes caused by one factor, and sometimes caused by multiple comprehensive factors. Seemingly complex, in fact, all burrs caused by molding parameter settings can be attributed to pressure. When the injection pressure exceeds the locking force set by the machine or the local bearing strength of the mold, burrs will be produced. Around the sprue, parting surfaces, and insertion holes with insufficient strength are highly likely to produce burrs

first, The V/P switch is too late.

Generally, when the injection molding is just right to fill the entire structure of the product, switching to holding pressure is the most ideal. If the switching is too late, the mold cavity pressure will rise sharply, and excessive pressure will easily cause burrs, and even lead to product deformation, oversized dimensions, mold sticking, top damage, and a series of other problems.

second, The injection speed is too fast.

The injection process is similar to the unlocking process of the machine, and the speed setting generally follows the principle of "slow fast slow", especially the injection speed at the end. If the speed impact is too fast, the pressure in the mold cavity will quickly reach its peak. In cases where the mold gap is too large or the locking force is insufficient, burrs will appear.

third,The holding pressure is too high or the holding speed is too fast.

Excessive holding pressure or too fast holding speed can quickly squeeze plastic into the mold cavity during the holding process, resulting in a sharp increase in mold cavity pressure, excess pressure, and the formation of burrs around the gate or even the entire analysis surface. More seriously, it can lead to mold expansion. If the product structure allows, a small pressure (less than 10%) and a short holding time (about 0.5 seconds for products with a thickness of 1.5mm or more) can be set in the first stage of holding pressure to buffer the transition of V/P switching, which can effectively prevent burrs. The setting of holding pressure generally follows a principle: the plastic melt in the mold cavity should be filled first at the low temperature position, and then at the high temperature position. The locations with low temperature are generally distributed at the end of filling, where the adhesive thickness is thinner, and at the parting surface. Therefore, the holding pressure of the front section should not be set too high, and the holding pressure of the rear section should be used as much as possible to solve local shrinkage or size problems. When adjusting the machine, gradually increase the pressure setting from low to high. It is recommended to increase it by 5% -10% every cycle until a reasonable pressure value is found

Excessive temperature of plastic melt can also cause product burrs. When the temperature of plastic melt is too high, its viscosity will gradually decrease, its flowability will improve, and the required locking force per unit area will also increase. In the case of large local gaps or insufficient locking force in the mold, burrs will appear. The reasons for the actual temperature increase of plastic melt are also multifaceted. Setting the temperature of the material tube too high, measuring too much glue, using too thick a screw, having a long cycle, excessive back pressure, and too fast a speed can all lead to an increase in the temperature of the plastic or directly cause a decrease in viscosity. When the product has burrs, these parameters should be checked in a timely manner.

In addition to the above issues, the fluidity of different plastics is determined by their own characteristics, and the requirements for the assembly clearance of various components of plastic molds and the locking force of the machine are also different. In the early stage of plastic mold opening, it is necessary to conduct an evaluation and fully assess the distribution of product gates, so as to produce qualified products with the lowest injection pressure possible. To ensure stable and normal production of the product and achieve the desired service life, it is necessary to fully evaluate the structure and strength of each part of the mold. Often, in the design of molds, cost considerations are taken into account to save costs in manufacturing. However, in the subsequent injection molding production, stable molding cannot be achieved, and even greater damage to the mold may occur. Further repairs and repairs will only lead to a vicious cycle.