The Lifters Design Standard
1. The lifter is mainly used to form the internal undercuts of a molded plastic part, and at the same time it also offers ejection function. The mechanism features a simple structure but poor rigidity and a short travel distance. The typical structure is shown as below: Most injection mold company usually apply the lifter structure as shown . The lifter employs the 8407 steel with a hardness of up to HRC50-52. There should be a distance of 1 – 3mm from the angle lifer to the product, with a clearance of 0.1mm on each side of the base made of the 738 steel, while the length tolerance is +1.5mm and +1.0mm on the top and bottom respectively. At the end … Read more
Injection mold sliders designing
1. When designing the injection mold sliders, the biggest clearance between the slider and the product should be at least 2 – 3mm. The inclination of sliders should be kept between 15 and 25 degrees, and the inclination of the guide pin should be 2 degrees smaller that of the wedge. The available diameters of the guide pin are 6mm, 8mm, 10mm and 12mm, with the min and max values being 6mm and 12mm respectively. If a slider width is larger than 60 mm, deployment of 2 angle pins needs to be considered; if the width exceeds 80mm, a guide bar needs to be placed under the slider in middle. If the injection mold sliders is too high, the starting … Read more
Guide Pins of plastic injection mold
There are many types of guide pin structures in plastic injection mold application, among which the standard structural design is shown in the figure below. A guide pin has to serve as the cylindrical surface of concentric circles of different diameters. Based on structural dimensions and material requirements, a round steel bar with an appropriate size can be directly selected as the material. In addition, the technical requirements of guide pins need to be satisfied during the machining process. Fig. 8-2 Structural Shape of a Guide Pin Technical Requirements of Guide Pins (1) At the joint between the guide pin and the fixed mold plate, the diameter concentricity tolerance should not exceed 1/2 of the diameter tolerance in the working … Read more
Mold texture
Mod texture Definition Texturing refers to the process that produces various patterns on the surface of a metal product through chemiosmosis, such as stripes, images, wood grain, leather pattern and stain, etc., while also including sandblasting, which means spraying glass sands directly onto the surface of a metal product. The Purpose of Mold Texture Improve product appearance. The texturing process is able to camouflage part of the shrinkage, welding line, parting line and steps of slider, etc. Product surface strength can be improved via texturing and sandblasting. Varieties of Mold Texture Sand Pattern Characteristics: Fast process, low cost and able to produce fine and 2D patterns. Satin Pattern Characteristics: Fast process and able to be applied to a plane surface. … Read more
A Brief Introduction to Ejector Pins Design
The Purpose of Ejector pins: Eject the molded part from the injection mold. Considerations for the ejection system: 1. Ejector pin holes should be at least 3/32” away from other holes; 2. At least a clearance of 1/32” for pin holes on the ejector plate; 3. At least a clearance of 1/64” for pin holes on the mold plate; 4. All ejector pins should adopt the standard dimensions; the ejector base cannot be ground lower; 5. During the injection molding process of nylon, LDPE or PP, the diamter of each ejector pin must be measured, because flash might occur when the clearanc between the pin and the hole is greater than 0.02mm 6. All ejector pin holes must be vertical … Read more
Commonly Seen Mainstream Injection Molding Machines Brands
The injection molding machine industry has experienced rapid development across the whole globe. Especially, in the era when Chinese manufacturing industry develops at a very fast pace, many Chinese and foreign injection machine brands are widely used in enterprises which produce plastic products. Among them, the more famous ones include Chen Hsong from Hong Kong, Victor Taichung from Taiwan, Haitian/Haitai/Bochuang from mainland China, Mitsubishi/Toshiba/Sumitomo from Japan, and Demag/KRAUSS MAFFEI from Germany. Comparatively speaking, Japanese injection molding machines enjoy the longest service life while German ones follow the highest safety standards. (1) German Demag Injection Molding Machine Demag is a world famous injection molding machine brand of the German Demag Ergotech. Its main characteristics include: the hydraulic mold clamping structure and … Read more
Lifters or Sliders for Undercuts on Four Sides?
As mold designers, we are all aware that, in normal circumstances, lifters are created for inner undercuts and sliders are created for outer undercuts. However, when we have undercuts on all 4 sides of a product, which makes it impossible to release the product by force, how should the mold be designed? See the following figure for the product. Shall we create lifters or sliders? Now, let me explain the mold design solutions for such products to all of you. Design analysis When coming across such products, we will firstly consider whether it is possible to create lifters. However, analysis shows that the undercuts in the 4 corners will not be able to be released with the help of lifters … Read more
Injection pressure,holding pressure and back pressure
1．Injection Pressure Injection pressure is exerted by the hydraulic mechanism of the plastic injection molding system. This pressure is transferred from the hydraulic cylinder to the molten plastic through the molding screw, under which the molten plastic will be pushed to flow into the mold sprue (also known as the primary runner of some molds), the primary runner and the sub-runner via the nozzle of the plastic injection molding machine, and then finally get into the mold cavity through the gate. This process is referred to as the injection molding process or the filling process. The purpose of the pressure is to overcome the resistance occurring when the molten plastic is flowing; or to put it another way, the resistance … Read more
How to set the hold pressure?
The setting of hold pressure is aimed to prevent resin backflow, while at the same time compensating for resin shrinkage caused during the cooling process, so as to achieve the optimal molding outcome. If the holding pressure is set too high, the product will be prone to flash, over filling or stress concentrating near the gate, etc.; on the other hand, if the holding pressure is too low, excessive shrinkage and dimensional instability will be likely to occur. Holding pressure only works well along with the settings of pressure switchover point and holding time in the plastic injection molding process. Insufficient holding pressure will lead to: 1. dents; 2. bubbles; 3. increased shrinkage rate; 4. decreased product dimensions; 5. larger … Read more
Material Change and Color Change tips during injection molding production
Changing material or color in the injection molding process certainly deserves in-depth discussion. A quick color or material change cannot only save time, but also drastically bring down the production cost. 1)Color change – a same material In principle, when injection molding factory change the color of a same material, change from light to dark is usually easier than that from opaque to transparent. The regular color change procedure is described as below: Shut the feed inlet located in the lower part of the feed hopper; Perform several empty shots, until the previous material is cleared from the barrel; Feed the new material into the hopper; Open the feed inlet, and pull the screw back and forth for a dozen … Read more