tailieunhanh - Injection Mold Design Engineering phần 2

tuy nhiên, việc thiếu phân tích kỹ thuật cơ bản trong thiết kế khuôn mẫu thường xuyên kết quả trong các khuôn có thể thất bại và yêu cầu làm lại mở rộng, sản xuất moldings của chất lượng kém, hoặc là ít hiệu quả chi phí hơn có thể có được có thể. Thật vậy, nó đã được ước tính trên trung bình 49 là 50 khuôn mẫu yêu cầu một số sửa đổi trong quá trình bắt đầu nấm mốc. | Mold Cost Estimation 47 data for machining and labor rates are provided in Appendix D though application specific data with the negotiated machinist s rate should be used if this data is available. The cavity machining time is driven by the size and complexity of the cavity details to be machined as well as the speed of the machining processes used. In theory the exact order and timing of the manufacturing processes can be planned to provide a precise time estimate. In practice however this approach is fairly difficult unless the entire job can be automatically processed for instance on a numerically controlled The cavity machining time is estimated as the sum of the volume machining time tcavity volume and the area machining time tcavity area. To take application specific requirements into account the cavity machining time is then multiplied by a complexity factor fcavity complexity to consider geometric complexity as well as a machining factor fmachining then divided by an efficiency factor machining-efficiency havity_machining havity_volume havity_area machining-efficiency cavity_complexity machining The cavity volume machining time is a function of the volume of material to be removed and the material removal rate. To provide an approximate but conservative estimate the assumption is made that the removal volume is equal to the entire volume of the core and cavity inserts. This may seem an overly conservative estimate but in fact much of the volume must be removed around the outside of the core insert and the inside of the cavity insert. The material removal rate is a function of the processes that are used the finish and tolerances required as well as the properties of the mold core and cavity insert materials. To simplify the analysis a geometric complexity factor will later be used to capture the effect of different machining processes and tolerances needed to produce the required cavity details. As such the volume machining time captures only