The length of the plastic bags produced by the bag-making mechanism is different. What's wrong?

- Mar 13, 2021-

1. Order

The business department of Shanghai Yifu Packaging Manufacturing Enterprise received a new order with a quantity of 2 million three-sided sealed bags. The customer information is shown in the table.

Table 1 Order information

Single number


client's name

A food company

product name

196g instant high-calcium protein tofu flower packaging bag

product structure


Product specification


2. Order analysis

After receiving the order, the salesperson confirms the quotation, and then prepares the raw and auxiliary materials according to the production and processing needs, and after the quality inspection department accepts them, they follow the production process of the tofu flower packaging bag.

3. Product Quotation

The sales price of plastic packaging bags is mainly composed of three parts: material cost, production loss and the company's gross profit, namely:

Flexible packaging product quotation = packaging material cost + production loss + corporate gross profit (due to fluctuations in the price of raw materials in different periods, only the calculation formula is given, and no specific numerical statistics are made.

1. Cost of packaging materials

①BOPP material cost

Unit price per square meter: unit price×density×thickness/1000

Weight per square meter: per square meter × density × thickness

②Printing and processing cost

The full-page printing ink is calculated as 8g/㎡, and the full-page printing is calculated as 128g/㎡.

Unit price per square meter: unit price × ink volume/1000

Weight per square meter: per square meter × density × thickness

③CPP material cost

Unit price per square meter: unit price×density×thickness/1000

Weight per square meter: per square meter × density × thickness

④Compound processing cost

The cost of the dry base glue amount = the dry base glue amount × the price of glue solid content/1000

Solvent cost = amount of solvent × price of glue solvent/1000

2. Loss

The loss is related to the order quantity. The size of the three-side seal in this case is 255mm×190mm. According to the layout, the repeat length of the horizontal row is 190mm, and the number of horizontal rows is 2. The width of the middle and both sides is 10mm, which is the required film size. The width is 790mm and the circumference of the plate is 510mm, that is, 4 bags are printed every one rotation of the printing plate. The length of the film required for 200,000 bags is 25,500m, because the three-side sealing bag production process is printing-composite-bag making. Divide.

①Printing loss

It is known that the new order test loss of this manufacturer is 1500m, and the old order test loss is 500m. In this example, the loss rate is 1500/(25500+1500)=5.6% based on the new order calculation.

②Compound loss

The compound loss is specifically about 1.5% for one compound, 3% for two times, and 4.5% for three times. This case is a one-time composite, that is, the loss is about 1.5%.

③Bag-making loss

In production, if the number of bags made is more than 50,000, the loss is about 1.5%, and if the number of bags is less than 50,000, the loss is about 2%. In this case, it is 200,000, and the loss is 1.5%.

④Edge loss

Calculated according to the width of the three-side sealing bag, the width of the film required in the production is 190×4=760mm, but the width of the printed film is 790mm, that is, the edge loss is 30/790=3.8%.

3. Gross profit

Enterprises also need to consider the cost of auxiliary materials used in production (such as paper core, tape, etc.), labor costs, water and electricity costs, management costs, transportation and profits when setting sales prices, according to the complexity of the bag processing technology , Companies generally add 10% to 40% of gross profit. Due to the relatively simple structure of the bag, the gross profit can be positioned at 20%.


4. Sales price

Based on the above analysis, the quotation of the composite membrane is finally determined.

Fourth, raw material procurement and testing

According to customer requirements, combined with the company's actual production, formulate the performance requirements of the raw materials used in the tofu flower packaging bags, product packaging bags, etc., and the corresponding project testing methods and standards.

1. Testing of raw and auxiliary materials

According to the corresponding routine testing items of the main raw and auxiliary materials, and according to national standards, industry standards, and corporate standards, relevant tests are done on BOPP, CPP, inks, adhesives, and solvents.

2. Printing plate making

According to the bag specifications and material requirements, determine the printing color number, plate week, and plate factory of the bag. The printing plate is produced by a professional plate making company.

5. Product production

1. Requisition of raw materials: Determine the requisition amount of raw materials according to the number of orders, product specifications, typesetting and the loss ratio of the composite process, and the bag-making process.

2. Production process: determine the printing, compounding and bag making process

6. Performance testing of semi-finished products and finished products

Semi-finished printing inspection items: color, overprint error, dots, pattern layout, ink adhesion and light distance.

Composite semi-finished products inspection items: appearance, composite initial bonding strength, section flatness, light distance.

Finished bag inspection items: length deviation, width deviation, sealing width deviation, bag pattern position deviation, bag foot deviation, punching position deviation, tearing position, appearance quality, edge sealing quality.

The inspection items of the finished bag: tensile breaking force, elongation at break, composite peeling force, sealing peeling force, pressure resistance, drop resistance, quantity.

Seven, packaging and storage

The finished bags made by printing, compounding, and bag-making processes are randomly inspected by the quality inspection department according to a certain proportion. After passing the products, the finished products are packaged according to the process requirements, and the outer packaging bags are arranged and placed in the specified storage place for temporary storage. Ensure that the seal is flat and the appearance is good.

The packaged products are stored in the warehouse and placed in the corresponding area neatly. The stacking should meet the sanitary requirements. Regular inspections should be carried out. The floor should be dry, ventilated and clean. Take measures to prevent rodents and insects. And give a clear mark.