Dispensing technology

Technical parameters affecting dispensing quality

Precision dispensing needle, plastic dispensing needle, dispensing nozzle, dispensing syringe

The process defects that are easy to appear in product dispensing are: unqualified glue point size, wire drawing, glue impregnation, poor curing strength, easy to fall off, etc. To solve these problems, we should study the technical parameters as a whole in order to find a solution to the problem.

1. Size of dispensing amount

According to work experience, the diameter of glue point shall be half of the product spacing. This can ensure that there is enough glue to bond the components and avoid excessive glue. The dispensing amount is determined by the length of time. In practice, the dispensing time should be selected according to the production situation (room temperature, glue viscosity, etc.).

2. Dispensing pressure

The dispensing equipment provides a certain pressure to the needle tube (glue gun) to ensure the glue supply. The pressure of the dispensing needle determines the glue supply and glue outflow speed. Too much pressure is easy to cause glue overflow and too much glue; If the pressure is too small, intermittent dispensing and leakage will occur, resulting in product defects. The pressure shall be selected according to the nature of glue and working ambient temperature. High ambient temperature will reduce the viscosity and improve the fluidity of the glue. At this time, it is necessary to reduce the pressure value, and vice versa.

3. Needle size

In practice, the inner diameter of the needle should be about 1 / 2 of the diameter of the dispensing point. In the dispensing process, the dispensing needle should be selected according to the product size. Different needles should be selected for products with different sizes, which can not only ensure the glue dot quality, but also improve the production efficiency.

4. Distance between needle and working face

Different dispensing machines use different needles, and some needles have a certain degree of stop. Before each work, calibrate the distance between the needle and the working face, that is, z-axis height calibration.

5. Viscosity of glue

The viscosity of glue directly affects the quality of dispensing. If the viscosity is high, the glue point will become smaller, even drawing; If the viscosity is small, the glue point will become larger, which may dye the product. During dispensing, select reasonable pressure and dispensing speed for glue with different viscosity.

6. Glue temperature

Generally, epoxy resin glue shall be stored in a refrigerator at 0 ~ 5 ℃ and taken out half an hour in advance to make the glue temperature consistent with the working environment. The use temperature of glue shall be 23 ℃ ~ 25 ℃; Ambient temperature has a great impact on the viscosity of glue. When the temperature decreases, the viscosity increases, the glue flow decreases accordingly, and wire drawing is more likely to occur. When other conditions are the same, the ambient temperature difference of 5 ℃ will cause a 50% change in the glue output. Therefore, the ambient temperature of the dispensing nozzle should be controlled. At the same time, the ambient temperature should also be guaranteed. If the temperature is too high, the glue point is easy to dry and affect the adhesion.

7. Curing temperature curve

For the curing of glue, the general manufacturer has given the temperature curve. In practice, higher temperature shall be used for curing as much as possible to make the glue have sufficient strength after curing.

8. Bubble

The glue must not have bubbles. A small bubble will cause many products to have no glue; When replacing the rubber hose in the middle of each time, the air at the connection shall be emptied to prevent empty beating.

9. Fluids requiring special settings

Instant glue: safety piston and Teflon lined metal needle are used for water-based instant glue, conical oblique needle is used for thick instant glue, and PP needle is used if flexibility is required;

UV glue: use amber syringe, white piston and inclined needle (which can block ultraviolet rays). If other kinds of needles are used, please order needles that can block ultraviolet rays;

Light curing adhesive: use black opaque needle cylinder to avoid photosensitivity;

Anaerobic glue: 10cc syringe and white PE universal piston are used;

Sealant and paste fluid: if the rebound of white piston is serious, please use safe movable type and inclined needle.

The adjustment of various parameters shall be carried out from point to surface. The change of any parameter will affect other aspects. At the same time, the defects may be caused by multiple aspects. The possible factors shall be checked one by one.

Classification of dispensing equipment

① According to the operation mode: manual dispensing equipment, semi-automatic dispensing equipment and full-automatic dispensing equipment.

② By glue: single liquid dispensing equipment, double liquid dispensing equipment, multi-component dispensing equipment, etc.

③ By application: thread dispensing equipment, horn dispensing equipment, mobile phone safety key dispensing equipment, patch dispensing equipment, board eraser, etc.

④ According to glue characteristics: silicone dispensing equipment, UV dispensing equipment, SMT red dispensing equipment.

Semi automatic dispensing machine

There are two modes of semi-automatic dispensing, manual and pedal, which can quantitatively dispense the glue, and has the function of vacuum suction. The negative pressure can be adjusted to 0.6kg. The dispensing needle nozzle can ensure that the glue with low concentration will not drip and leak, and can also prevent the drawing of glue with high concentration.

Automatic dispensing equipment

The production efficiency of automatic dispensing device of full-automatic dispensing machine is several times to more than ten times that of manual dispensing. Man machine interface, intuitive and convenient operation. It has spatial three-dimensional function. It can not only walk any chart on the plane, but also walk spatial (multiple planes) three-dimensional chart. It has USB interface and program transmission between machines. It has vacuum suction function to ensure no glue leakage and wire drawing. It can be equipped with dispensing valve and large capacity pressure barrel (when the key glue amount is large). In order to improve the productivity efficiency and the competitive advantage of enterprise production, odd talk equipment can be added according to the needs of the process. Suitable for silicone, EMI conductive adhesive, UV adhesive, AB adhesive, quick drying adhesive, epoxy adhesive, sealant, hot adhesive, grease, silver adhesive, red adhesive, solder paste, heat dissipation paste, anti solder paste, transparent paint, screw fixing agent, etc.

Main uses: bonding, pouring, coating, sealing, filling, dripping, linear / arc / circular / irregular pattern coating, etc.

Two component dispensing equipment

The two-component dispensing equipment is also called double liquid dispensing machine, AB dispensing machine, etc. the double liquid dispensing system (glue filling machine) is composed of three parts: two pressure barrels (mainly used to provide and store two different glues to the dispensing valve), AB dispensing valve (mainly used to mix the two glues in different proportions and solidify after reaction within a certain time), Another is the controller, also known as dispensing machine (mainly used to control the dispensing quantity, dispensing frequency and accuracy)

1. By adjusting the different strokes of the dispensing valve cylinder and combined with the output air pressure of the two pressure barrels, the proportion of glue can be easily adjusted.

2. Static mixing pipes of different lengths and sizes shall be selected for mixing degree to ensure full and uniform mixing of glue.

3. The microcomputer high-precision dispensing controller is selected, which has the functions of digital display and memory storage to make the dispensing accuracy more accurate, and has multiple operation modes such as automatic, quantitative and cyclic. More convenient to use.

4. The cleaning of the pressure barrel is convenient and fast, and the inner tank can be configured according to the needs of users.

Thread dispensing machine

Gluing method: glue the screw teeth one by one; The dispensing needle mouth can be glued accurately and uniformly, and the number of teeth and gluing position can be set arbitrarily. The improved gluing structure avoids the gluing needle scratching the product, and avoids the jumping of teeth (there are teeth coated with glue at the gluing position) due to the error of the product. The humanized design avoids the hidden danger of personal injury caused by the equipment. Optional automatic material return function, uniform and stable glue dispensing, small volume, convenient operation, non-metallic material storage device, and the glue will not thicken with time;

Process parameters: suitable screw diameter: m5-m30 screw, screw length: within 100mm. Gluing width: screws within 50mm, gluing speed: 2-5 seconds / piece.

Suitable glue: all kinds of pre applied glue (such as thread sealant, anaerobic glue, thread locking glue, anti loosening glue, pipe thread sealant, dry film glue, liquid raw material belt).

Scope of application: screws, bolts, studs, nuts, plugs and various pneumatic joints.

Silicone dispenser

Silica gel dispenser is designed for silica gel and other glue with poor fluidity and high viscosity. It is especially suitable for the products with 330 ml / barrel of silica gel and glass glue.

Function description and product features:

1. There are two modes: automatic quantitative mode and manual mode.

2. The time of each glue dropping is controlled by the timer, and the glue is discharged regularly and quantitatively to ensure the same amount of glue dropping each time.

3. Air pressure, select the appropriate time and needle nozzle, so as to change the amount and time of glue dropping each time, which is suitable for different needs

4. The input air pressure is 2.5 ~ 7 kg / C ㎡ and the output air pressure is 0.01 ~ 5.5 kg / C ㎡.

5. Use with pressure bucket.

Maintenance method of dispensing machine

The daily maintenance of dispensing machine directly affects the service life of dispensing machine. The daily maintenance of the dispensing machine has a great impact on the service life of the dispensing machine, including the smoothness in the normal use process. The following are the daily maintenance steps of the dispensing machine:

1. When replacing the rubber seed, the pipeline needs to be cleaned. At this time, first close the feed valve, open the discharge valve, discharge the remaining rubber in the rubber barrel, close the discharge valve, open the feed valve, pour the cleaning solvent into the rubber storage barrel, activate the machine body, and press out the solvent for flushing according to the normal operation mode.

2. If the air pressure intake is abnormal and water vapor is found, please eliminate the water vapor in the pressure regulating filter or check whether the air pressure source is abnormal. Before the glue dispenser is used in large quantities, please try it in small quantities to master the use skills of the product so as to avoid errors. When the test is OK, use the double liquid glue dropping machine or double liquid glue filling machine for mass production; The vacuumizing system vacuumizes and defoamers the glue to eliminate the bubbles generated during mixing, or stands for 10-20 minutes before use, so as to eliminate the bubbles generated during mixing in time, and the more glue mixed together.

3. Please wipe the machine regularly to increase its service life. The more glue is mixed together, the faster the reaction will be and the faster the curing speed will be. Therefore, it is necessary to mix glue reasonably according to the actual production situation, otherwise it will cause a waste of glue. Eliminate accidents and improve production efficiency. Nowadays, liquid control technology and dispensing equipment are widely used in various production fields in modern industry.

4. When the machine is out of service for a long time, the power supply should be unplugged, which can not only prolong the service life of the machine, but also save a lot of electricity. With the needs of rapid industrial development, liquid control technology and dispensing equipment are constantly developing to ultra-high precision control, diversification and specialization.

Note: the dispenser shall be cleaned after each use, and all visible places shall be wiped with alcohol. It is best to light oil or butter on the frequently moving parts to maintain lubrication. If it is not used for a long time, the glue must be polished, otherwise it will solidify in the dispenser and have to be cleaned.

Common problems and solutions of automatic dispensing machine

With the development of economy, dispensing machines are widely used in electronic industry, lighting industry, automobile industry, industrial electrical, solar photovoltaic, construction engineering and other industries. The most common problem encountered by the automatic dispensing machine is the valve problem. The following are effective methods to solve the problems that often occur when the glue valve is used:

1. Rubber nozzle blocked

Cause: the pinhole of the automatic dispensing machine is not completely cleaned, The dispensing needle impurities are mixed in the patch glue, the hole is blocked, and incompatible glue is mixed, resulting in less glue output from the glue nozzle or no glue spots.

Solution: replace the clean needle and patch glue with good quality. The brand of patch glue should not be mistaken.

2. Rubber valve dripping

Cause: the diameter of the needle used in the dispensing machine is too small. Too small needle will affect the exhaust bubble action of the rubber valve when it is used, affect the flow of liquid and cause back pressure. As a result, drip will be formed shortly after the rubber valve is closed.

Solution: just replace the larger needle to solve this problem. In addition, the air in the liquid will drip after the rubber valve is closed. It is best to exclude the air in the liquid in advance, or use the glue that is not easy to contain bubbles, or centrifuge the glue for defoaming before use.

3. The flow rate is too slow

Cause: the pipeline of dispensing machine is too long or too narrow, the air pressure at the pipe orifice is insufficient, and the dispensing flow rate is too slow.

Solution: change the pipeline of dispensing machine from 1 / 4 "to 3 / 8". If there is no need, the shorter the pipeline, the better. In addition, the rubber port and air pressure should be improved, so as to speed up the flow rate.

4. There are bubbles in the fluid

Cause: due to excessive fluid pressure and too short valve opening time, the dispenser may infiltrate air into the liquid, resulting in bubbles.

Solution: reduce the fluid pressure and use a conical oblique needle.

5. Inconsistent glue size

Cause: the pressure cylinder or air pressure of the fluid stored in the dispensing machine is unstable, The dispensing needle resulting in uneven glue output and inconsistent size.

Solution: avoid using the low pressure part of the pressure gauge. The control pressure of the glue valve shall be at least 60psi to ensure stable glue delivery. Finally, check the glue delivery time. If it is less than 15 / 1000 seconds, it will cause unstable glue delivery. The longer the glue delivery time, the more stable the glue delivery.

The above content is about the common fault causes and solutions of automatic dispensing machine. I believe you all know. These common problems of automatic dispensing machine can be large or small. Users can quickly solve these problems as long as they master the correct solutions.

How to solve the problem of wire drawing when using high viscosity glue in automatic dispensing machine

Generally, low viscosity glue is mostly used for large-area application, such as film covering, potting, large-area bonding, etc. medium viscosity glue is easy to operate and suitable for most bonding, sealing and other operations. High viscosity glue is difficult to spit out, with weak or almost no fluidity. It is suitable for cofferdam, reinforcement, etc. Some products must use high viscosity glue due to process requirements. In the process of dispensing, due to high viscosity, sometimes wire drawing will affect the quality and beauty of dispensing. So how to solve wire drawing?

Complete solution

If the company has very strict requirements for product quality, it can be considered from the aspect of hardware. The dispensing valve is equipped with a valve specially for high viscosity fluids, such as imported screw valve, which provides the glue viscosity value to the manufacturer. The manufacturer will help you match the type according to the glue viscosity value to achieve the perfect dispensing effect. Of course, the price of screw valve with high viscosity will be more expensive, But it can help you solve the problem of wire drawing perfectly.

Other solutions

1. Glue opening delay

When opening the rubber head, because there is a distance between The dispensing needlethe rubber outlet of the rubber head and the rubber valve, there is no glue between this section. If you start moving immediately after opening the rubber head output, it will lead to a short section of glue shortage at the beginning of the track. To prevent this situation, after opening the glue, delay for a period of time, wait for the glue to flow out, and then perform the subsequent movement. This delay time is called glue opening delay.

2. Glue closing delay

After closing the rubber head, there is still glue flowing between the rubber outlet of the rubber head and the rubber valve. If it moves immediately after closing the rubber head, glue tailing may be formed. In order to prevent this from happening, after closing the glue head, The dispensing needle delay for a period of time and wait for the glue to flow out before performing subsequent actions. This delay time is called glue closing delay.

3. Drawing height

Due to the high viscosity of some glues, the glue wire can be broken only by lifting it slowly at a constant speed for a certain distance, which does not affect the gluing track. This distance is called the drawing height.

4. Lifting height

When the glue dispensing of one track is completed and moves to the starting point of the next track, in order to prevent the rubber head from hitting the needle, lift the rubber head up a certain height at the end point to ensure that the rubber head is safe from hitting the needle, and then move to the starting point of the next track,