The basic knowledge of injection mould
Mold design process and key points
1. Product drawing data and CAD technical requirements (2D&3D)
2. Product shrinkage rate
3. Molding machine beer machine data
4. Product evaluation analysis (DFM)
5. Mold flow analysis
6. 2 d Layout
7. 3 d Layout
Calculation formula of clamping force of injection molding machine
Clamping force is an important parameter of injection molding machine, which is the clamping force exerted on the mold by the injection molding machine. The clamping force and injection sample, to some extent, reflect the capacity of the machine to process products, often used as the main parameters of the machine specifications. According to the vertical projection area of injection molding products on the formwork, calculate the clamping force P: clamping force = locking force constant X product projection area, that is, P= KP *S
P - clamping force (T)
Kp - modulus locking force constant (t/cm2)
S - vertical projected area of the product in the formwork (cm2)
S= product length L* width B* number of holes N
Kp values are listed in the common plastic name Kp in the table below
For example: suppose the projection area of a product in the vertical direction is 410cm2 and the material of the product is PE, calculate the required clamping force. The above formula is calculated as follows:
P=Kp*S=0.32X410=131.2(t) optional 150T moulding machine
It should be noted that: the clamping force is insufficient, the product production flying edge or can not be formed, and if the clamping force is too much, resulting in a waste of system resources, and will make the hydraulic system components under high pressure for a long time to work, may be premature aging, mechanical structure too fast wear. Product evaluation is the pre-evaluation of product structure, thickness, drawing, parting line, thimble arrangement, risk, etc. It is a written form of communication with customers. Specific see DFM
Mold flow analysis
Mold flow analysis (moldflow) derived from the concept and Taiwan on the other side of the term, actually refers to using data simulation software, through the computer for injection molding simulation, simulation of the mold injection molding process, some of the data results, through these results to evaluate feasibility of mould, improve the mold design and product design, plastic mold commonly used software moldflow, Moldex3D etc
Mold flow analysis can find the possible defects of the mold in advance, saving the cost of mold test and mold modification. For example, the optimal pouring scheme is optimized to help determine the best hot runner entry point location, to help confirm whether there is "shrinkage" phenomenon, combined with the position of the line, to reduce warpage deformation, improve cooling efficiency and shorten molding cycle, etc., have real benefits for high-quality mold production. In general, the advantages of doing model flow analysis are as follows:
1. Save money, save unnecessary mold testing and mold modification costs;
2. Save time, shorten mold forming cycle and production cycle, and improve the success rate of the first mold test;
3. High quality, find possible defects in the mold in advance, avoid welding after mold test;
The mould of qualifying
Mold layout is based on the requirements of customer production, molding machine and product evaluation report to quickly draw the mold structure, mold size, etc. on 2D drawings. The mold layout is the outline of the mold design. The mold layout is the basis of the mold quotation. The product structure can be quickly modified on the mold layout. For structural designers, if you can arrange the mold layout map to grasp the mold quotation will be very helpful.
Pay attention to the key points in the mold test process
1. Whether the mold can be opened and closed smoothly.
2. Whether the mold ejection is smooth or not, and whether the product can drop automatically
3. Pay attention to the sprue position and feeding method of the mold, the size of the sprue and the size of the mold cavity (choose the appropriate pressure, speed and quantity).
4. After the mold is heated up, open and close the mold several times, and carefully check whether there is any excellent phenomenon in all parts of the mold. If no one can continue.
5. During mold test, first try out the short shot product (confirm the combination line and exhaust).
6. After the product is filled, let the quality personnel determine the size and appearance.