Quotation Composition Details and Cost Accounting Method for Injection Molding Processing
Injection molding quotation is not a simple estimation of unit product price. It needs comprehensive calculation of raw materials, mold amortization, machine energy consumption, labor, waste loss, management cost, packaging and logistics. Combined with order quantity, product size, material type and quality requirements, refined accounting is required. Many customers only pay attention to the unit selling price and ignore the cost differences brought by different order quantities and appearance standards, which easily leads to losses from low quotation or lost orders from over-high quotation. Clarifying various cost details and mastering standardized accounting methods can make quotations more objective and reasonable, helping suppliers and buyers quickly evaluate project budgets.
1. Raw Material Cost Accounting
Raw materials account for the highest proportion in the total cost of injection molding, generally fifty to seventy percent. The accounting should consider raw material unit price, single product net weight and the loss ratio of runner waste. The single-piece raw material consumption weight equals the sum of product net weight and gate-runner weight multiplied by the material loss coefficient. The price varies greatly among different raw materials. Ordinary PP and ABS are low-priced, while PC, PPS, PEEK, food-grade and flame-retardant raw materials have much higher procurement costs. Runner waste generated in production can reduce raw material cost if recycled and mixed into production. If customers forbid regrind addition in products, the loss ratio should be increased accordingly. Meanwhile, raw material procurement freight and warehousing costs need to be considered. Drying treatment for hygroscopic raw materials also consumes energy, which is included in raw material related costs.
2. Mold Cost Amortization Method
Mold cost includes one-time mold opening fee and amortized cost allocated to each product. The total mold price covers mold core steel, mold base, processing cost, polishing, heat treatment, spare parts and mold trial rectification cost. The amortized amount is determined by the total order quantity. The larger the total order volume, the lower the single-piece mold amortization. For small-batch orders, the mold cost is usually borne by purchasers at one time. For large-volume long-term orders, mold cost can be shared among hundreds of thousands or millions of products, and the single-piece amortization is almost negligible. During accounting, mold maintenance cost should also be estimated. Long-term mass production will incur mold surface polishing, insert replacement, exhaust groove cleaning and other maintenance expenses. Such hidden costs need to be taken into quotation consideration.
3. Machine Production and Energy Consumption Cost
The cost of injection molding machines is calculated according to clamping tonnage and production cycle. Larger tonnage means higher equipment depreciation and electricity cost. First calculate the single molding cycle including injection, holding, cooling, mold opening and ejection, to get the output per hour. Equipment cost includes equipment depreciation, hydraulic oil, cooling water and air compressor energy consumption. Power consumption of auxiliary equipment such as cooling towers, dryers and shredders in workshops should also be allocated to each plastic part. Night shift production and peak electricity price increase will further lift energy consumption cost. If the product molding cycle is long and the output per unit time of the machine is low, the single-piece machine cost will rise.
4. Labor Cost Accounting
Labor cost includes salaries of machine operators, quality inspectors, mold maintenance technicians and material managers. The accounting is based on the number of personnel allocated to each machine, hourly wage and machine utilization rate. Production lines with automatic manipulators require less labor input. Products requiring manual picking, gate trimming and full appearance inspection will significantly increase labor cost. Appearance parts and precision plastic parts need full inspection, and inspection working hours are calculated separately. Utilization rate also affects labor cost. Frequent mold change and shutdown due to defective products reduce effective output and raise allocated labor cost per piece. Mold change working hours and mold trial working hours need to be separately included in quotation for small-batch orders.
5. Defect Loss and Quality Control Cost
A certain proportion of defective products exist in any injection molding production, so defect loss must be reserved in quotation. Ordinary structural parts have low defect rates, while high-gloss appearance parts, medical precision parts and insert injection products have obviously higher defect loss. Defective products consume raw materials and occupy machine and labor working hours. Quality control also includes investment in testing tools such as calipers, two-dimensional detectors and inspection jigs, as well as inspection working hours and sample inspection fees. When customers require third-party testing, material certificates and outgoing inspection reports, corresponding testing fees should also be incorporated into the quotation system.
6. Packaging, Logistics, Management and Profit
Packaging cost is calculated according to customer requirements. Ordinary cartons and plastic bags have low cost, while anti-static bags, blister trays and moisture-proof packaging are more expensive. Logistics cost is calculated by delivery location, cargo weight and transportation mode. Enterprise management cost covers workshop rent, administration, technical design and business communication and other indirect expenses, usually allocated to single products at a fixed proportion. Finally, reasonable tax and expected profit are reserved, and the final quotation is adjusted combined with market conditions.
Control methods, collect complete product drawings, material specifications, appearance standards, estimated total order quantity and delivery location before quotation. Prioritize mold flow analysis to predict molding difficulty and estimate molding cycle and defect rate. Distinguish one-time mold opening cost and mass processing unit price, and list quotation items separately for transparent details. For long-term orders, agree on annual price adjustment mechanism to cope with raw material price fluctuation. Regularly review the difference between actual production cost and quotation estimation, continuously optimize accounting models and reduce quotation errors.
Summary
Injection molding quotation is composed of raw materials, mold amortization, machine energy consumption, labor, defect loss, packaging logistics and management expenses. Order quantity, product structure complexity, raw material type and quality standard are core variables affecting the final price. Standardized cost accounting methods can avoid loss risks brought by empirical estimation. Clear quotation details also facilitate communication between suppliers and buyers on project budgets and guarantee stable project implementation.
