"Injection start-up is not equal to making money", if control / management work is not in place in  injection molding production, there will be low production efficiency, high defect rate, large number of seats, large material consumption, bulk returns, artificial damage to mold, compression mold, broken screw heads, delayed delivery, frequent machine repairs / mold repairs, high defect rates, many scraps, large waste of raw materials and even safety accidents. It will cause huge economic losses to company, and company's profits will be greatly reduced, or even loss . Let's calculate cost-related accounts.

Under premise of ensuring product quality, injection molding cycle time should be as short as possible. The shorter injection molding cycle and the greater number of production, the lower manufacturing cost per unit product. Injection cycle time includes: injection time, pressure holding time, cooling time (melting time), mold opening time, ejection time (including residence time), door opening time, pickup time, door closing time, mold locking time, etc. (special circumstances also includes shooting table forward/backward time and release agent spray time).
Main methods to shorten injection molding cycle time are: reduce wall thickness of plastic parts / runner size (to shorten cooling time), reduce mold opening and closing distance / ejector pin stroke, quickly remove product, manipulator operation, speed up opening / closing of safety door, reducing phenomenon of sticking, correct selection of cooling time, reasonable setting of mold opening / closing speed and ejector speed / number of times, etc.
Example analysis: Standard injection cycle time of a plastic part (one out of four) is 24 seconds. If actual injection cycle time is extended to 28 seconds, production time of one day is 23 hours. Results of economic benefit analysis are as follows:
Standard daily output is: 23 * 4 * (3600 ÷ 24) = 13800 pcs.
Actual daily output is: 23 * 4 * (3600 ÷ 28) = 11829 pcs.
A day's output will be reduced by 1971pcs., Which is equivalent to a reduction of 3.3 hours of production time a day, and manufacturing cost of plastic parts will increase (3.3 ÷ 23) * 100% = 14.3%.
If an enterprise has 80 injection molding machines, processing profit of one machine is 50 yuan per hour, and it will earn 165 yuan less every day.
Monthly economic loss of enterprise is: 80 * 165 * 30 = 396,000 yuan
Economic loss of enterprise for one year is: 39.6 * 12 = 8.364 million yuan

 

When quoting to customers, each injection molding company usually calculates output and manufacturing cost based on total number of mold cavities; if in injection molding production process, technicians inadvertently damage mold cavity or a mold cavity is of poor quality and needs to block production, it will cause a significant increase in injection molding production costs, a decrease in profits and even a loss.
Example analysis: An order for a plastic part is 300,000, each profit is 0.05 yuan, and number of mold cavities in production is eight. Because injection technician accidentally injured a mold cavity, cavity needs to be blocked for production. Cycle time is 20 seconds which is calculated as 23 hours of production time a day. Results of its economic benefit analysis are as follows:
Standard daily output is: 23 *(3600 ÷ 20) *8 = 33120 pcs.
Actual daily output is: 23 *(3600 ÷ 20) *7 = 28980 pcs.
Standard production days for 300,000 output are: 300000 ÷ 33120 = 9.06 days
Sctual production days are: 300000 ÷ 28980 = 10.4 days
It takes 1.34 days to complete production of this order, and it will earn 2219 yuan less.
Production profit of plastic parts will become: 0.05-0.0074 = 0.043 yuan (86% of original profit); if an injection workshop has an average of 5 sets of molds per day to block a mold cavity, enterprise will reduce profit by 370,000 yuan a year.

"Waste is the biggest waste", if there is a high defect rate in injection molding production process, a large amount of plastic parts are scrapped or returned, loss of raw materials, electricity costs, labor, equipment loss (excluding other costs) will be great.
Example analysis of a plastic part (two cavities), weight of a single piece is 30g, raw material price is 20 yuan / kg, injection profit is 0.08 yuan, defect rate in production process is 10%, and injection cycle is 25 seconds. Results of its economic benefit analysis are as follows:
Raw material cost of each product is: 20 *30 ÷ 1000 = 0.60 yuan
Daily production quantity is: 23 *3600 ÷ 25 *2 = 6624 pcs.
If daily electricity, labor and other expenses of a machine require 1,000 yuan, average processing cost of each plastic part is: 1000 ÷ 6624 = 0.15 yuan / piece
Loss caused by 10% defect rate in one day is: 662 *0.60 + 662 *0.15 = 496.3 yuan
Profit from one day's production is: (6624－6624 *10%) *0.08 = 477 yuan
Actual profit produced in one day is: 477-496.3 = -19.34 yuan
That is: a daily loss of 19.34 yuan (excluding mold / machine loss and site fees);
If nozzle material can be recycled, profit per machine per day will be reduced by more than 100 yuan;
For an enterprise with 100 injection molding machines, economic loss for one year is: 100 *360 *100 = 3.6 million yuan

 

If mold maintenance work is not done properly, mold failures will often occur during production process, frequent mold shutdown and maintenance will be required. This will not only affect smooth progress of production and stability of plastic parts quality, but also cause economic losses to enterprise (such as: mold maintenance costs, plastic raw materials/power consumption, labor costs, and loss of machine shutdown, etc.).
According to statistical analysis, average maintenance cost of each mold is 350 yuan, waste of raw materials / electricity is 100 yuan, labor cost of upper and lower molds is 50 yuan, and cost of machine stoppage loss is 200 yuan (about 700 yuan).
An example analysis of 100 machines in an injection molding workshop, average number of mold repairs per month in production of each machine is 4 times, and results of economic benefit analysis are as follows:
Economic loss caused by one-month mold maintenance is: 4 *100 *700 = 280,000 yuan;
Loss caused by one year is: 12 *28 = 3.36 million yuan;
Therefore, each of our injection technicians must enhance awareness of mold maintenance, set clamping force / opening speed / ejector parameters reasonably, set low-pressure protection parameters correctly, clean, lubricate, maintain and prevent rust in mold during injection molding process.

 

According to statistics, cost of raw materials accounts for 70% to 85% of cost of large plastic parts, 50% to 65% of cost of medium-sized plastic parts, about 30% of cost of small plastic parts. Cost of raw materials is main part of production cost of injection molding. Injection molding production process should strengthen control of nozzle materials, waste products, plastic heads and raw materials; links that cause loss of raw materials in injection molding production are: mixing wrong materials, using wrong color powder, super single ingredients, mixing of nozzle materials, mixing wrong materials, adding wrong materials, baking agglomeration, baking barrels not completely cleaned, raw material pollution, high defect rate , long machine adjustment time, unclassified processing of plastic head (flattening and reuse), opening and closing caused by machine repair / mold repair, improper production scheduling, frequent machine replacement in production, replenishment production, long-term processing problems, incomplete classification of nozzle materials, large number of mold trials and nozzle leakage.
According to statistical analysis of injection molding cost, average loss of 2kg of raw materials produced by converting a set of molds is 20 yuan / kg per kilogram of raw materials. Minimum cost lost of raw materials for each set of molds (including transfer, color change, injection supplement, raw material replacement, machine and mold repair, trial mold, transfer machine, etc.) is 40 yuan. Average cost of package of wrong materials (including: mixing wrong materials, using wrong color powder, playing wrong materials, adding wrong materials, super single production, super single ingredients, raw material pollution, mixing of nozzle materials, etc.) is 500 yuan, and some special engineering plastics cost up to 100 yuan / kg (cost of raw materials per package is 2500 yuan).
Example analysis: An enterprise has 100 injection molding machines, each machine has an average of 10 mold changes (referring to mold repair, machine repair, refueling / coloring, machine replacement, etc.) within a month in production. Results of its economic benefit analysis are as follows :
Cost of raw materials wasted in one month is: 100 *30 *10 *40 = 1.2 million yuan
Raw material waste caused by one year is as high as: 120 * 12 = 14.4 million yuan
Above does not include other aspects (such as: misuse of materials, return of goods, mixing of spout materials, mismatching of materials, addition of wrong materials, over-single replenishment, raw material pollution, etc.), resulting in loss of raw materials.
If an enterprise with 100 injection molding machines consumes 1 kg of raw materials per machine on average, loss of raw materials caused by one year is: 100 *1 *20 *360 = 720,000 yuan.
Therefore, all staffs in injection molding workshop should increase awareness of saving raw materials, increase management and control of raw materials, improve work quality and responsibility of personnel in each position, reduce waste of raw materials caused by various links in the injection molding production, and create more profits for enterprise.

 

Injection molding machine is a key equipment for injection molding production. Price of each machine is an average of 350,000 yuan, accounting for about 60% of total investment of injection molding department. If maintenance of injection molding machine is not done properly, there will be wear of hinge, broken screw head, broken green column, nozzle leakage, hydraulic oil pollution, oil pipe leakage, hydraulic system failure, electronic components burned out (or shortened life), damage to inner wall of barrel / screw, damage to rubber ring (check ring), damage to mechanical parts, frequent machine shutdowns and repairs, low machine utilization, expensive repair / replacement parts, unstable process conditions, high defect rate in production (large scrap), low production efficiency and shortened service life of injection molding machines (about 1 ~ 2 years), etc., causing great waste and high costs.
Example analysis: An injection molding company has 100 injection molding machines, average maintenance failure occurs once a year for each machine. Each maintenance fee is 1500 yuan. If lubrication and maintenance of injection molding machine is not good, average life of injection molding machine is shortened by 1.5 years. Results of its economic benefit analysis are as follows:
Maintenance fee required for injection molding machine in one year is: 100 *1500 = 150,000 yuan;
Cost loss caused by shortened service life of injection molding machine is: 1.5 *100 *35 = 5.25 million yuan;
If calculated based on 10-year service life, annual loss is: 525 ÷ 10 = 525,000 yuan;
Above waste does not include waste caused by increase in defective products caused by unstable product quality, shutdown of repair machine, replacement of hydraulic oil, overhaul of machine, replacement of screw / feed tube and other aspects. Therefore, injection molding technical management personnel should enhance maintenance awareness of injection molding machine, prevent machine from malfunctioning, do a good job in use / lubrication / maintenance of injection molding machine, extend its service life, and reduce costs.

"Product quality is life of an enterprise". Plastic parts return and high defect rate are the biggest waste, which not only affects reputation of enterprise, but also causes great economic losses to enterprise. If quality control of products in injection molding is not good, there will be a high defect rate, a lot of scrap products, low output, returns and rework, delays in delivery, and even customer orders will be lost, competitiveness of enterprises will decline.
If there are bulk returns in injection molding production, losses will be even greater, and all "materials, labor, and expenses" that are put into production will be lost; especially for return of finished products due to quality of plastic parts, some companies paid hundreds of thousands, millions and tens of millions of dollars for this.
For example: There is a plastic electronics factory in Dongguan. When finished product was shipped to a foreign customer, product was returned due to cracking of plastic parts, and it lost $ 3.2 million at a time. If quality control is not good and defect rate in injection molding production exceeds 8%, there will be a loss (especially for plastic parts that cannot be recycled for injection nozzle materials).
Example analysis of an injection molding company, when producing a transparent electrical product bottom case (larger), because direction of bevel screw column is reversed during mold repair, result is that plastic parts produced in two weeks (14 days) are scrapped, daily injection processing cost is 2500 yuan, total loss of raw materials is 100 bales, and results of its economic benefit analysis are as follows:
Raw material loss fee is: 100 *25 *20 = 50,000 yuan;
Processing fee loss is: 2500 *14 = 35 thousand yuan;
Due to delay in delivery of order, finished product needs to be air-shipped abroad, and an additional air freight of 150,000 yuan is paid. Total loss caused is: 5 + 3.5 + 15 = 235,000 yuan;
If assembled product is returned and customer cancels order, economic loss will be even greater. "High-quality products are produced and managed ", staff in all positions in injection molding department need to enhance quality awareness, improve product quality by improving work quality, reduce return risks, and reduce costs.

Efficiency of injection molding is a comprehensive reflection of injection molding machine / injection mold maintenance, injection mold quality, rationality of injection molding process, injection molding technology / management level and staff quality. Production efficiency is low, quantity of a certain plastic part injected in a certain period of time is small, production cost is high. Without high efficiency, there is no high benefit. Main methods for improving efficiency of injection molding are: improving production tools (IE), improving working methods, using efficient tools and equipment, improving work quality and work efficiency of personnel in various positions, achieving automated production, reducing production failures, reducing number of  mold / machine repairs, strengthen maintenance of molds and injection molding machines, improve injection molding technology and management level, make preparations before production, reduce defect rate, shorten cycle time, reduce time to deal with problems, etc.
Example analysis: During injection molding production process of an injection molding company (with 100 machines), production shutdowns / mold repairs / baking materials often occur, defect rate is high, and there are many production problems. Average production efficiency is only 80%. Results of its economic benefit analysis as follows:
If injection molding production efficiency is 90% as standard, based on average production of 3,000 molds per day (23 hours), output of company’s 100 machines per day due to reduced production efficiency is: 100 *(90% -80% ) *3000 = 30,000 molds, which is equivalent to quantity produced by 10 injection molding machines. If average economic benefit created by each machine is 1,000 yuan per day,
Profit reduced in one month is: 30 *10 *1000 = 300,000 yuan;
Profit reduced in one year is: 30 *12 = 3.6 million yuan;
Therefore, improving efficiency of injection molding production can not only bring huge profits to enterprises, reduce production costs, but also reduce investment in injection molding machines, molds, peripheral equipment, tools and workshops.
Total equipment investment that can be reduced is: 10 *30 + 10 *5 + 10 + 5 = 3.6 million yuan
It can be seen that if concept of management personnel of injection molding enterprises is in place, through improvement of skill training and technical management, efficiency of injection molding production can be improved, which will bring extremely high returns on economic benefits.

Modern enterprises are faced with an era of "migrant workers shortage" and it is difficult to recruit workers. In the past, some companies mistakenly believed that injection molding industry was a labor-intensive industry, and used a large number of injection workers to perform post-processing. Average number of production workers per injection molding machine for backward injection management companies exceeded 2 or more; In general injection molding companies, number of workers per injection machine is 1.5 on average; injection companies with high technical and management levels (of the upper middle class) have an average of 1.2 workers per injection machine; for injection molding enterprises with high degree of automated production (top grade), average number of workers per machine is less than one.
As long as product / mold design is scientific and reasonable, degree of automation of injection molding production is high, injection molding production can be completely unmanned; 20 years ago, there was an unmanned injection molding workshop controlled by a central computer system.
Main measures to reduce number of seats are: optimize product design, improve nozzle form, use three-plate mold structure, use Robot, use efficient tooling / fixtures, reduce amount of post-processing, reduce unnecessary movements, protect mold (so as not to produce a sharp edge ), improve processing tools, quantify post-processing quantitative indicators, strengthen operation training, use skilled workers, improve processing procedures and methods, improve packaging methods, etc.
An example analysis of an enterprise with 50 injection molding machines. Before improvement, average manpower of each injection molding machine was 2.2. After 6 months of system transformation and training / upgrading, average manpower of injection molding machine is now 1.3. Results of benefit analysis are as follows:
Now number of injection molding machine workers in enterprise is: 50 *1.3 *2 = 130 people (two classes)
Before improvement, number of injection molding workers in enterprise was: 50 *2.2 *2 = 220 people (two classes)
Reduced manpower of enterprises after improvement is: 220-130 = 90 people
Based on average cost of each worker (including food, housing, water, electricity, wages, etc.) is 1200 yuan / month, labor cost of injection molding company reduced in one month is: 90 *1200 = 108,000 yuan
One year can save labor costs: 12 *10.8 = 1.296 million yuan
It can be seen that, by improving injection molding technology / management level, reducing number of machine seats, it is one of effective ways for injection molding enterprises to reduce production costs for improving economic efficiency and reducing labor expenses.

Injection molding is an industry with extensive knowledge, technicality and experience, and it is a systems engineering. It involves plastic performance, plastic parts structure, injection mold design / processing, injection machine structure / function, injection molding process adjustment, analysis of common injection molding defects, plastic additives (color matching), injection quality control, injection engineering management, plastic parts performance testing, injection workshop management and safety production management.
At present, professional skills of most injection molding company employees (such as: product structure design engineers, mold design engineers, mold manufacturing personnel, trial mold engineers / technicians, injection molding technology / management personnel and quality engineers / quality inspection personnel, etc.) are low(Compared with foreign countries), professional knowledge is lacking, and enterprises have less training on relevant personnel's professional knowledge of injection molding. For a long time, injection molding technology / management personnel have not had opportunity to learn professional knowledge and improve their capabilities. Their ability to analyze / handle problems is not good. Factors to conduct a comprehensive analysis of injection molding defects and production problems, only work based on experience, blindly adjust machine.
If company's injection molding technology / management level is low, it will appear in injection molding production: low production efficiency, high defect rate, large number of seats, large material consumption, bulk returns, large number of trial / modification times, artificial damage to mold, compression mold, broken screw head, delayed delivery, many mold / machine failures and safety production accidents, which cause huge economic losses to enterprise, resulting in high production costs and a decline in competitiveness of enterprises.
Only by comprehensively and systematically training knowledge of injection molding technology management, continuously improving work ability and quality of personnel in various positions can we fundamentally prevent problems in injection molding production, reduce various wastes, and reduce cost of injection molding production.

1) There are many times of trial / modification;
2) Unreasonable staffing;
3) Production of arrears or over orders;
4) Improper production scheduling;
5) Do things based on experience only (blind tuning machine);
6) Unreasonable product / mold design;
7) Wrong way of doing things;
8) Control of auxiliary materials;
9) "Fire-fighting" management (run after the problem);
10) Outdated ideas (unwilling to learn new knowledge).
Cost of injection molding refers to all costs in production process, including: labor, electricity, molds, raw materials, toner, maintenance costs, equipment wear, tools, packaging materials and auxiliary materials. Main factors affecting economic efficiency of injection molding are: low injection mold / injection machine maintenance awareness, poor control of nozzle material, many times of mold repair / machine repair, large number of seats, low occupational skills of various positions, poor work quality, low production efficiency, long time for machine adjustment, low problem analysis / handling ability, work based on experience only, backward concepts, low injection molding technology/management level, running behind problem, inadequate prevention work, poor working methods, mixed raw materials, many waste products, long production cycle, clogged mold cavity, improper machine arrangement, production of overdue / over-single orders, return and rework, many times of repairing / modifying, and inadequate training.