I'd like to share with you a relatively new machining process and quotation. Is your factory operating at this price?
01 Processing equipment
1. Ordinary lathes are mainly used to process shafts, discs, sleeves and other workpieces with rotating surfaces. They are the most widely used type of machine tool processing in mechanical manufacturing (can achieve an accuracy of 0.01mm).
2. Ordinary milling machines can process planes, grooves, various curved surfaces, gears, etc., and can also process more complex surfaces (can achieve an accuracy of 0.05mm).
3. Grinding machines are machine tools that grind the surface of workpieces. Most grinders use high-speed rotating grinding wheels for grinding, and a few use other grinding tools and free abrasives such as oilstones and sanding belts for processing, such as super finishing machines, sanding belt grinders, grinders and polishers (can achieve an accuracy of 0.005mm, and small parts can achieve 0.002mm).
4. Fitter Fitter operations mainly include filing, sawing, marking, drilling, reaming, tapping and threading, scraping, grinding, straightening, bending and riveting, etc.
5. CNC lathes mainly process batch products, high-precision parts, etc. (can achieve an accuracy of 0.01mm).
6. CNC milling machines mainly process batch products, high-precision parts, complex parts, large workpieces, etc. (can achieve an accuracy of 0.01mm).
7. The electrode used for wire cutting is brass wire, and the medium wire is molybdenum wire. The wire cutting has high processing accuracy and good surface finish. Process some fine holes, fine grooves, etc. (the wire cutting can achieve an accuracy of 0.003mm, and the medium wire cutting can achieve an accuracy of 0.02mm).
8. Spark machine EDM can process materials and complex-shaped workpieces that are difficult to cut by ordinary cutting methods (such as groove corners, small holes, deformed holes, and processing on cemented carbide). There is no cutting force during processing, and no defects such as burrs and knife marks and grooves are generated. Not affected by material hardness, not affected by heat treatment conditions (can achieve precision of 0.005mm).
02 Process Flow
The machining process specification is one of the process documents that stipulates the machining process and operation methods of parts. It is written into a process document in a prescribed form under specific production conditions to guide production.
The machining process of parts is composed of many processes, and each process can be divided into several installations, stations, steps and tool paths.
Which processes a process needs to include is determined by the structural complexity of the processed parts, the machining accuracy requirements and the production type.
Different production quantities have different processing technologies.
Process knowledge
1) Holes with an accuracy of less than 0.05 cannot be made by general milling and require CNC processing; if it is a through hole, it can also be wire cut. 2) Fine holes (through holes) after quenching require wire cutting; blind holes require rough machining before quenching and fine machining after quenching. Non-fine holes can be done before quenching (leaving a quenching allowance of 0.2 on one side). 3) Slots with a width of less than 2mm require wire cutting, and 3~4mm slots with a very deep depth also require wire cutting. 4) The minimum allowance for rough machining of quenched parts is 0.4, and the allowance for rough machining of non-quenched parts is 0.2. 5) The thickness of the coating is generally 0.005~0.008mm, and the processing should be based on the pre-plating size.
03 Processing time
The time quota is the time required to complete a process, which is an indicator of labor productivity. According to the time quota, production operation plans can be arranged, cost accounting can be carried out, the number of equipment and staffing can be determined, and the production area can be planned. Therefore, the time quota is an important part of the process specification.
The time quota should be determined based on the production and technical conditions of the enterprise, so that most workers can reach it after hard work, some advanced workers can exceed it, and a few workers can reach or approach the average advanced level after hard work.
With the continuous improvement of the production and technical conditions of the enterprise, the time quota is revised regularly to maintain the average advanced level of the quota.
The time quota is usually determined by the combination of process personnel and workers, summarizing past experience and referring to relevant technical data. Or it can be calculated by comparing and analyzing the time quota of workpieces or processes of similar products, or it can be determined by measuring and analyzing the actual operation time.
Process time = preparation time + basic time
Preparation time is the time consumed by workers to familiarize themselves with process documents, receive blanks, install fixtures, adjust machine tools, disassemble fixtures, etc. Calculation method: estimate based on experience. Basic time is the time consumed to cut metal.
04 Quotation cost calculation method
Processing part cost = (material cost + processing fee) * 1.2 [1.2 coefficient includes management fee]
Equipment cost = (processing part material cost + processing fee + purchased product cost + assembly and debugging fee + design fee) * 1.2 [1.2 coefficient includes management fee]
Material cost = weight (density * volume) * unit price (yuan/kg)
Processing fee = process time * unit price (yuan/hour)
Japanese purchase product cost (yuan) = purchase price (yen) / exchange rate Domestic purchase product cost is based on supplier quotation
Design fee = work time * unit price (yuan/hour)
Quotation information
1) Lathe: 60 yuan/hour. 2) Milling machine: 60 yuan/hour. 3) Grinding machine: 60 yuan/hour. 4) Fitter: 80 yuan/hour. 5) Machining center: 60~120 yuan/hour. 6) CNC lathe: 60~120 yuan/hour. 7) Spark machine: 80~150 yuan/hour. 8) Wire cutting: 60~150 yuan/hour; small pieces start at 80 yuan, large pieces are based on area: 0.06~0.08 yuan/mm². 9) Fine hole discharge: carbon steel, tungsten steel, φ0.3 and above 1 yuan/mm, φ0.3 below 2~3 yuan/mm; φ0.3 and above 1.8~2 yuan/mm. 10) Management fee: cost price*0.2.
