injection molding cost

The cost of injection molding is influenced by a multitude of factors, but is mainly comprised of the following:

1. Raw material cost – This cost is quite easy to be calculated. Ask the raw plastic material supplier how much 1kg costs, multiply the product weight by 3% of loss rate, and then multiply the raw material price to get the cost of the raw material;
2. Machine cost – Regarding this cost, ask a plastic injection molding factory what the hourly processing rates of different plastic injection molding machines are? Assume that the processing cost per hour for a 100-ton plastic injection molding machine is 60 RMB/hour, then the cost per minute is 1 RMB; at this point, it is necessary to calculate the injection molding cycle of the plastic part, as well as the number of cavities of the mold. Assume the injection cycle of the plastic part that you are evaluating is 30 seconds, then there are 60/30 = 2 shots in 1 minute, which means that two rounds of molding can be achieved in 1 minute. And, assume it is a two-cavity mold, then the machine cost of the plastic part is 1 yuan divided by the number of shots in 1 minute, and then divided by the number of cavities in the mold. So, the final machine cost is 1 RMB/ 2 shots / 2 cavities = 0.25 RMB / piece.
3. The secondary processing cost includes painting/screen printing/electroplating, etc. You may ask their respective processing plants for the figures.
4. Packaging costs – According to the size and volume of the plastic part, the cost of the carton/bag can be obtained;
5. Transportation cost – According to the delivery location and the cost of the container truck, the transportation cost per piece can be obtained by dividing the total loading amount;
6. Other expenses: Because the above costs do not include the costs of indirect personnel or other related personnel, it is necessary to add some fees according to the different conditions of each factory;

The profit equals the total sum of the six items mentioned above multiplied by the profit rate of 10-30%. Then you can get the final cost of a plastic part. The profit should be determined on the basis of the situations in each factory and the order amount.

A Injection mold price calculation method!

Mold price calculation

1. Empirical calculation of mold price = material fee + design fee + processing fee & profit + VAT + mold trial cost + packaging & transportation fee, of which the percentages are usually:

Material fee: materials and standard parts account for 15%-30% of the total mold price;

Processing fee & profit: 30%-50%;

Design fee: 10%-15% of the total mold price;

Mold trial: for large and medium-sized molds, the cost can be controlled within 3%, and for small-sized precision molds, within 5%;

Packaging & transportation fee: can be calculated in real terms or by 3%;

VAT: 17%

2. Material coefficient method – The mold material fee can be calculated according to mold size and material price. Mold price = (6~10) * material fee

Plastic mold = 6 * material fee

Die-casting mold = 10 * material fee

Cost accounting for plastic injection molding

Cost of a molded part = material fee + processing fee + packaging fee + transportation fee

Description:

1. Material fee = [(1 + material loss) * product weight * batch size + material loss during machine adjustment + normal scrap rate * product weight * batch size *] material price / batch size

The material loss is generally 3%-5%; the material loss during machine adjustment and the normal scrapped product usually weigh 5,000g-15,000g.

2. Processing fee = (machine adjustment time / batch size + molding time / number of mold cavities) * processing cost of the injection molding machine

At present, processing cost of injection molding machine in Shenzhen is calculated by tonnage (domestic equipment)

Tonnage of Machines	80	120	160	200	250	300	400
Cost per hour(RMB)	35-45	65-85	80-110	95-140	150-200	180-220	250-300

Calculation of molded part price – Specifically, the quote for a plastic injection molded part is shown as follows:
Product unit price = material price + processing cost
Material cost = (actual weight + loss) * material unit price
Processing cost = molding cycle * unit price (seconds) ÷ number of cavities (that is, the price of each piece)
If packaging is specifically required, the cost of packaging needs also to be added.
Basically, these are the three major categories.
The material price is relatively simple: PP or ABS is directly calculated as the price * product weight, while that of a colored piece can be calculated on the basis of the raw material price. The price of a black part can be calculated according to the specific recycled materials or product requirements. The processing cost is correlated to the number of mold cavities, the molding cycle and the weight of the product; the machine cost can be detailed to price per second according to machine tonnage. Assume that the number of mold cavities is large, the weight is heavy and the molding cycle is short, the processing cost will be low, accordingly leading to a low unit price.

On assumption that a PP product weighs 50g, make calculations respectively using 1*1 / 1*2 / 1*4. The product is a colored piece made of the new material.cycle time is 60 second.the injection machine is 100 Ton,and cost 60RMB per hour.PP Raw material is 12 RMB per kg.

1*1(1 cavity mold):   

Material cost:0.05×12=0.6RMB ;  processing cost:60/60/1=1RMB; so injection molding price:0.6+1=1.6RMB

1*2(2 cavities mold): 

Material cost:0.05×12=0.6RMB ;  processing cost:60/60/2=0.5RMB; so injection molding price:0.6+0.5=1.1RMB

1*4(4 cavities mold):

Material cost:0.05×12=0.6RMB ; process costing:60/60/4=0.25RMB; so injection molding price:0.6+0.25=0.85RMB

The cost control of plastic injection molding also involves many factors. It must be controlled from the equipment, application process, raw material, as well as management and technology to achieve the optimal efficiency at the lowest cost.

Tools and Components Control:

Tools – All screws, nuts, nylon hoses and hose clamps, etc. in the packaging workshop must be controlled with a corresponding method, or great waste will be caused!

 

Mold Application Control:

Production Process:

• Appropriate clamping pressure during the adjustment process – It is appropriate as long as the product meets the requirements, and the clamping force is able to ensure that the injection pressure does not force the core and the cavity open to cause flashing.
• The ejection speed needs to be properly controlled. The ejection system itself is a system that should avoid as much friction as possible. If the speed is too fast, the system will inevitably be damaged.
• Make full use of the low-pressure protection feature of the injection molding machine, so that there is chance for the mold to be damaged.
• Too-high or uncontrolled injection pressure, speed, holding pressure and back pressure are also important factors that cause damage to the mold or affect its service life!
• Mold temperature control is also very important. Excessive mold temperature will cause the individual parts inside the mold to swell and the compatible space to change, thus finally damaging the mold. The too-low mold temperature is not able to ensure the mold temperature to reach a relative balance after the mold absorbs the heat generated by the melting of the plastic, thus eventually causing rust and damage due to long-term moisture in local areas!
• Human factors: Especially when such issues as mold adhesion or scratches and other common mold issues occur, a specialist is required to handle them. Do not arbitrarily authorize anyone to handle them casually.

Maintenance & Storage:

• During the production process, the moving parts such as the lifter, the side pin, the slider, the guide pin and the ejector pin must be thoroughly lubricated at least once a day, or more than twice a day in special circumstances.
• During hot-oil production, it is necessary to pay attention to the clamping of the mold and the partial swelling of the slider. During cold-water or icy-water production, the coolant must be cut off at least 15 minutes before shutting down the machine!
• Pay special attention to the matte-surfaced mold and the polished mold – don’t damage or scratch them, or it will be quite troublesome to repair them!

 

Application of the Injection Molding Machine:

Plastic Injection Options:

• Injection Volume:During the production process, the choice of injection molding machine is usually to ensure the molding quality. The weight of the product should be 25-75% of the total weight of the injected plastic, which is the recommended ratio. If the best product volume is required, the range should be lowered to 40- 60%.
• Wear- / Corrosion-resistant Barrels and Screws:If the glassfiber-reinforced hard plastic is selected, it is better to choose wear- / corrosion-resistant alloy barrels and screws. Wear tends to occur when common nitrided screws are employed: choose corrosion-resistant alloy screws and barrels for acidic materials, such as PVC and POM.

Cost Control during injection molding Machine Adjustment:

• Reduce wear and tear:If abnormal wear and tear is caused due to improper operations or other accidents during the adjustment process, the machine will not be able to operate properly for 12 years. Eventually, the daily wear and tear will increase greatly, and at the same time lead to incalculable and serious maintenance costs! To reduce abnormal wear and tear, it is necessary to strengthen the technical level of the technicians, as well as the knowledge of other workers.
• The choice for the switch point between injection and pressure holding is able to reflect the actual operation level of a technician in an injection molding workshop. When realizing that the most fundamental purpose of pressure holding is to compensate for the shrinkage, the injection time and pressure can be minimized to reduce wear and tear, as well as power consumption, thus finally achieving the requirements for cost control!
• The mold opening and closing process also reflects the actual operation level of a technician in a plastic injection molding workshop, because it fully reflects the connection between speed, time and energy consumption!

 

Material Cost Control:

The key to the cost control of a plastic injection molding workshop is the material control. If material control fails to reach the target, it will directly lead to a serious decline in profit. Any carelessness may lead to loss of profit.

Starting from the plastic materials release, control every detail to ensure zero material waste.

• The machine cleansing process: Firstly, the machine scheduler must schedule the production from light to deep colors, so that it is possible to eliminate the discoloration that may occur by using a deep color to cover a light color. When cleansing the machine, first try to cleanse the machine with prepared sprues or recycle materials, and then adjust the machine using the sprues of the material to be used. When the product reaches the required quality, the production officially starts.
• Machine adjustment process: Try to use the parameters and instructions provided by the flowchart, making the adjustment process a process of copying the book or inputting the parameters, thus simplifying the general adjustment process.