Because the gripping edge with a width of about 1cm on the printed sheet cannot be printed, and there are rules and color codes outside the scope of the finished product, so for general printed parts, the paper is first cut to be larger than the finished product, and then processed after printing. At that time, use a paper cutter or die cutter to cut off the surrounding waste paper.
If the indentation processing of the paper bag is made of thick cardboard instead of the indentation line, die cutting and indentation should not be carried out at the same time. Therefore, the paper bag is generally only indented and not die-cut.
If the paper edge is cut off with a paper cutter before creasing, it will affect the positioning accuracy of the creasing. If it is left to be cut after molding, it is not easy to cut neatly because the paper is deformed during molding. Therefore, the generally adopted method is to cut the paper into the unfolded size of the finished product before printing, and only perform indentation processing after printing, without cutting or die cutting.
Rectangular paper bags with length, width, and height respectively a, b, and h. The finished product size a, b, h and the finished product unfolded size A, B have the following conversion relationship: the unfolded length A=2×(a+b) + Side sticky mouth, unfolded width B= fold+h+ bottom, the side sticky mouth is generally 2cm, and the fold is generally 5cm.
When the paper size is tight, the side sticky mouth and fold can be slightly narrower, or slightly wider if the paper bag is large. The bottom of the paper bag is 0.5×b+the bottom sticking mouth. The bottom sticking mouth is about 1cm. If the paper bag is bigger, it can be wider.

The adjustable roll square bottom paper bag machine is used to make square bottom paper bags from the tube material. It uses the machine to complete the top gluing, raw materials into a tube, cutting, bottom indentation, bottom gluing, and bagging. The bottom is formed and the bag is discharged. It is an ideal equipment for producing food bags and handbags.
The whole machine is controlled by a computer central control system, touch screen display, servo motor controls the length of the bag, and can produce paper bags of various specifications.
The machine can adapt to the paper range, up to 230 bags per minute, or even higher speed,
Help customers effectively increase unit production capacity and obtain more profits.
Operation control system
Touch screen man-machine interface, regardless of correction, fine-tuning can be easily solved,
Alarms and operating status are displayed on the screen instantly for easy control.
Unwinding system
The loading and unloading of raw materials adopts pneumatic shaft clamping and hydraulic lifting structure.
Unwinding adopts automatic constant tension control, EPC automatic correction, variable frequency motor traction
Significantly reduce the roll registration adjustment time.
Perfect after-sales service, eliminating customers' worries. Accurately track printed materials, greatly reduce machine adjustment and setting time, and improve production efficiency.

In the United States and Japan, paper bags are the second only form of paper packaging to cartons. Paper bag is one of the oldest and most widely used packaging forms and has many advantages.
Convenience Among various packaging methods, paper bags are the simplest and most efficient ordinary packaging. In retail stores, salespersons can pack without skilled skills. The sealing operation of the bag mouth is simple, and the opening and retrieval is extremely convenient. The buyer can also do the packaging operation by himself.
Low price Among all packaging forms, except for packaging accessories such as straps, paper bags are undoubtedly the cheapest packaging containers, because paper bags have light weight and the cheapest shipping (except for heavy bag packaging).
The perimeter of the anti-pollution paper bag is completely closed, so it can effectively prevent dust and other harmful substances from polluting the contents. In addition, the harmful components in the paper are extremely small and will not pollute the contents, which is beneficial to food packaging.
The adaptability to the contents of the product is packaged in paper bags, and is not restricted by the shape of the product, and products of any shape can be packaged in bags.
Convenient to carry and transport Items packed in bags are very convenient to carry, transport, stack, store, and keep. After filling loose items, they can be placed upright, saving space.
Surface design The surface of the paper bag can be applied with various decoration designs, printing and coloring, etc., which can also increase the effect of product sales, advertising, and company promotion.
Discarded paper bags are easy to dispose. The bags can be reused after use, and can be recycled if they are not used. They are used as raw materials for paper making without causing pollution.
Of course, paper bags also have shortcomings: First, the paper bag itself is poor in self-supporting; second, it is poor in durability. If higher durability is required, paper materials with better performance can be used, and the cost will be slightly increased. In addition, convenient carton packaging is used to make up for the shortcomings of paper bags.
The paper bag material we use should preferably have the following properties: good moisture resistance, good flexibility, not easy to break, and also have renewable properties. In the past, kraft paper had better toughness; however, it had insufficient moisture resistance.
1. Types of commonly used paper bags
Envelope paper bag. The bottom does not form a plane, and it is often used to hold small and powdered goods;
Gusset bag. There are M-shaped crotch pleats on both sides, and the openings on both sides of the bag can expand the width of the crotch pleats. The bottom width of this bag is equal to the crotch width. After opening, a flat bag with the same bag length can hold more than twice as much stuff. , The most common in sales bags.
Square bottom bag and hexagonal bottom bag. Also known as self-opening bag, the bottom of the flat bag is folded and then glued into a bag with a square bottom or a hexagonal bottom seal. There is no crotch fold on both sides of the bag. This kind of bag can hold many things within the size range of the bottom surface.
The processing of the bottom of the bag is related to the position of the longitudinal seam of the bag body and the production method, and the manual and mechanism are generally different. This kind of bag is mainly used for packaging when selling goods.
Portable square bottom bag. The most common gift bags and shopping bags. It is generally made of kraft paper and white cardboard, which is relatively strong and comes with various handles.
2. The sealing of the bag mouth
All kinds of small paper bags should be sealed after filling the contents. The sealing methods include: folding and sealing, tape paper, labels, art paper labels, etc., pasted into a flat end; folding seal; metal strip sealing; rope ligation and other methods; sometimes it can double as a handle when using a rope ligation And for sealing.

1. Standard problem: In the past, manual bag gluing standards were not uniform. One person has one technique and one person has one standard. The portable paper bag machine has effectively solved this problem through the control mode of the combination of machinery and electrical appliances.
2. Benefit problem: pure manual gluing of bags, a large amount of people, large amount of glue, weak bonding, low efficiency; the advent of the portable paper bag machine, first of all, the difficulty of recruiting workers and the high wages of workers are resolved, and the amount of glue is saved. Calculating based on the production of 10,000 bags per day, it is possible to save one machine money in one year. At the same time, after the bags are glued, they can be pressed mechanically, which effectively avoids the phenomenon of weak bonding and opening.
The outstanding advantage of the food paper bag machine is that the food paper bag produced is non-toxic, tasteless, and pollution-free, and because the paper has good printing performance, it can print graphics and text according to user requirements. It is an ideal equipment for food packaging bags such as chestnut bags, fried chicken bags, hamburger bags, hand cake bags, small meatball bags, candied haws bags, beef jerky bags, etc.

1. Heat sealing temperature
The selection of the heat sealing temperature of the composite film is closely related to the performance and thickness of the composite substrate, the model, speed, and hot air pressure of the bag making machine, which directly affects the strength of the heat sealing.
The initiation temperature of the composite film is determined by the viscous flow temperature or melting temperature of the heat sealing material, and the high temperature of the heat sealing cannot exceed the decomposition temperature of the heat sealing material. The temperature between the viscosity flow temperature and the decomposition temperature is the heat sealing temperature range of the heat sealing material, which is a key factor that affects and controls the quality of heat sealing. The wider the heat-sealing temperature range, the better the heat-sealing performance, and the easier and more stable the quality control.
At the same time, the heat sealing temperature of the composite film cannot be higher than the heat setting temperature of the printing substrate. Otherwise, it will cause shrinkage and wrinkling of the heat-sealed part, reducing the heat-sealing strength and the impact resistance of the bag. The temperature resistance of the printing substrate is good, such as BOPET, BOPA, etc., increasing the heat sealing temperature can increase the production rate; the temperature resistance of the printing substrate is poor, such as BOPP, try to use a lower heat sealing temperature, and by increasing the pressure, reducing Production speed or choose low-temperature heat-sealable materials to ensure heat-seal strength. (Chongqing Renyi)
2. Heat sealing pressure
The hot air pressure is provided by the pressure spring on the bag making machine. The size of the heat sealing pressure is related to the performance, thickness, and heat sealing width of the composite film. Polar heat-sealable materials have higher activation performance, and the increase in temperature has a greater impact on the decrease in viscosity. Therefore, the required heat-sealing pressure is relatively small to prevent the molten material at the heat-sealed part from being extruded and affect the heat-sealing effect. However, PE and PP are non-polar materials with extremely low activation performance and high pressure required, which is beneficial to heat sealing strength and interface sealing.
The heat sealing pressure should increase as the thickness of the composite film increases. If the heat-sealing pressure is insufficient, the two films will be difficult to heat together, and it will be difficult to exhaust the bubbles sandwiched between the welds; if the heat-sealing pressure is too high, the molten material will be squeezed away, the weld edge will be damaged, and the root will be broken. When calculating the heat sealing pressure, the width and actual surface area of ​​the required heat sealing knife should be considered. The wider the width of the heat-sealing knife, the greater the pressure required. If the width of the heat-sealing knife is too wide, it is easy to cause air bubbles in the heat-sealed part, and it is difficult to heat-seal firmly. Generally, a hollow heat-sealing knife can be used to strengthen the heat-sealing fastness in the last seal. For heat-sealing knives with the same width, if the surface is engraved, the actual contact area is greatly reduced, and the pressure per unit area increases accordingly. This is beneficial for packaging bags with larger heat-sealing widths.
3. Heat sealing speed
The heat sealing speed reflects the production efficiency of the bag making machine, and is also an important factor affecting the heat sealing strength and appearance. The faster the heat-sealing speed, the higher the heat-sealing temperature should be to ensure that the heat-sealing strength and heat-sealing state reach the best value; under the same heat-sealing temperature and pressure, the slower the heat-sealing speed, the better the fusion of the heat-sealing material Full and firmer, but can not cause root breaking.
For domestically produced bag making machines, the length of the heat sealing time is mainly determined by the speed of the bag making machine. To increase the heat sealing time, the bag making speed must be reduced and the production efficiency must be reduced. If an independent frequency conversion motor is used to control the lifting and feeding of the heat-sealing knife, and the heat-sealing time is independently adjusted without changing the bag making speed, it will greatly facilitate the operation and quality control of the bag making machine.
4. Cooling
The cooling process is a process of shaping the weld just melted and sealed with a lower temperature under a certain pressure to eliminate stress concentration, reduce the shrinkage of the weld, improve the appearance of the bag, and increase the strength of the heat seal.
The cooling water of the bag making machine is generally tap water or circulating water at about 20°C. Too high water temperature, insufficient cooling knife pressure, poor cooling water circulation, insufficient circulation, etc. will lead to poor cooling and reduced heat seal strength.
5. Number of heat sealing
The longitudinal and transverse heat sealing of most bag making machines use hot plate welding. The number of longitudinal heat sealing depends on the ratio of the effective length of the heat sealing knife to the bag length. The number of transverse heat sealing is determined by the number of heat sealing devices on the machine. . Good heat sealing generally requires more than 2 heat sealing times. Most transverse heat sealing devices consist of 3 groups. In order to meet the heat sealing requirements of the wide side, transverse heat sealing devices are often added, and the number of heat sealing is increased to lower the heat sealing temperature and reduce the shrinkage phenomenon. For packaging bags of longer specifications, multiple feeding technology can be used to reduce the length of each feeding to one-half or one-third of the bag length, thereby increasing the number of heat sealing and improving the heat sealing effect, but it will reduce production Efficiency, so some bag making machines increase the length of the longitudinal heat sealing rod to increase the number of heat sealing and ensure the quality of heat sealing.
6. Heat sealing knife gap
The heat-sealing knife gap refers to the distance that the predetermined hot air pressure is transferred to the heat-sealing surface when the upper heat-sealing knife contacts the bottom plate. At the same film thickness and the same heat sealing speed, the heat sealing knife gap is small and the heat sealing time is relatively short, and the heat sealing strength of the product will be reduced. Generally, the heat-sealing knife gap is set at 1.0~1.5mm, which is related to the film thickness, transfer performance, and bag making speed.