Dispensing, called dispensing in English, is a process, also known as gluing, sizing, gluing, gluing, dropping glue, etc., is to apply glue, oil or other liquid, potting, drip onto the product, so that the product plays the role of sticking, potting, insulation, fixing, smooth surface and so on. This process has a very wide range of applications, and is an indispensable part of the automobile manufacturing process.
The dispensing process can be operated manually or with automated robots. Under normal circumstances, in automobile production, due to large output and high beat, robot automatic dispensing is basically selected. This process is efficient, but it is also expensive and technically difficult. Automatic dispensing is generally controlled by air pressure, and the glue is pushed out within a set time. The meter controls the time of each infusion, theoretically ensuring the same amount of infusion. By adjusting the air pressure, time and selecting the appropriate needle tip, the amount of injection can be controlled. However, in actual production, problems that may occur emerge in endlessly, which is a key technical difficulty.
The survey found that the following points are the factors that they think are most prone to problems in the dispensing process:
· Consistency of dispensing;
· Accuracy of dispensing;
· Equipment maintenance;
· How to speed up the beat;
· Waste of glue;
· Operator training;
· Rework and maintenance;
· Consistency of dispensing
Summarize the pain points and solutions of dispensing process
This problem is most common and intractable in small batch production. About 44% of the respondents said that due to small batch production, manual operation is often used instead of automated robots. With manual methods, consistency between each artifact is the biggest challenge. With operators changing all the time, consistency is the odd thing.
The consistency problem improved slightly when manufacturers used more advanced automated equipment for dispensing. Thirty-seven per cent of interviewees who used an air-powered benchtop dispenser identified consistency issues as a challenge. Thirty-two percent of respondents using pneumatic valves systems identified the issue of consistency as a challenge, Only 26% of those using positive-displacement dispensing systems said it was a challenge.
Of course, we cannot replace all complex problems with manual operation with automation equipment to solve, although improving the dispensing equipment can improve the problem of consistency, but following some simple guidelines can also make progress, such as the problem of bubbles. Because bubbles are one of the main culprits that destroy glue performance and consistency, we can find ways to reduce bubbles in the fluid. For example, a centrifuge is used to remove air from the fluid before dispensing; Or try to avoid thawing the frozen glue to prevent a large number of freeze-thaw gaps after the glue is frozen and thawed.
Precision of dispensing
Dispensing accuracy is also a point prone to problems. Very similar to dispensing consistency, 41% of manual operation respondents and 35% of pneumatic dispensing users consider dispensing accuracy to be a difficulty;
Accuracy issues are less apparent when using pneumatic valve systems such as diaphragm valves and needle distribution valves. Some manufacturers use advanced injection systems, such as electro-pneumatic injection valves and piezoelectric injection valves, which have greatly improved accuracy.
Recent advances in pneumatic dispensers have also helped in improving accuracy. Software improvements now allow many machines to do more than one bit of glue and can help speed up production.
Bubbles in the glue can also affect the accuracy of each dispensing. Removing air from the fluid before use is key to accurate dispensing.
Maintenance of equipment
Equipment maintenance has always been a challenge. It mainly includes equipment disassembly, cleaning, lubrication, and shutdown maintenance. Different from the above two points, the way of automatic dispensing increases the difficulty of equipment maintenance.
In 2017 and 2018, the maintenance of volumetric dispensing systems was considered the number one problem by 46% and 45% of respondents, respectively.
Meanwhile, for pneumatic valve systems, 39% and 33% of respondents in 2017 and 2018 respectively cited them as a problem.
In addition, 35% of respondents in 2018 found it difficult to maintain pneumatic injection valve system equipment.
It is not at all surprising that more respondents identified volumetric dispensing systems as a problem compared to pneumatic and jet valve systems. Positive displacement dispensing devices, such as positive displacement pumps, typically have more complex parts that require more time to remove and clean. The advantage of positive displacement systems is that they provide continuous, repeatable dispensing regardless of fluid viscosity or viscosity changes over time. The benefits outweigh the disadvantages of taking longer to clean compared to other types of dispensing systems.
Recent advances in dispensing technology, including pneumatic valves and piezoelectric injection valves, have reduced maintenance times through innovative product designs. A quick release snap integrated into the valve design allows the operator to quickly remove fluid while installing the valve into the automation system, eliminating the need to disassemble the valve to clean and return it to service, thus saving significant maintenance time. In fact, if the manufacturer prepares more than one fluid in advance, it can be seamlessly switched, thus minimizing downtime in a matter of minutes.
How to speed up the production beat
For some parts suppliers, because the product is in short supply, it can be sold as soon as it is produced, so improving production speed is the top priority. Any shutdown is equivalent to burning money. In 2018, about 44 percent of respondents said speeding up production was their number one challenge. Forty-three percent of respondents who use desktop automation systems report an urgent need to speed up production.
Usually, when a higher production volume is required, if we apply a desktop automation system, the robot can achieve batch dispensing by distributing the fluid, thus replacing the one-to-one mode, thus greatly increasing the production speed.
One of the reasons respondents identified production speed as a pain point for automated dispensing systems may be that the manufacturers of dispensing systems deliberately designed the robots to move at a slow speed so that they do not exceed a safety threshold and thus do not need to be sealed in a safety protection system.
The latest desktop dispensing robot is specially designed to shorten the dispensing cycle. These new robots are driven by ball screws rather than belts, allowing for faster and more precise positioning. Some models can achieve position repetition accuracy of ±0.003 mm.
Waste and training
The last thing worth mentioning is the waste of glue, operator training and rework and scrap.
Waste liquid waste glue seems to be a little waste, but the cost is not small over time. A common way to reduce glue waste is to use disposable dispensing parts, similar to syringe canisters and pistons, which are designed to prevent any glue from being left in the canisters after dispensing. Other parts are specifically designed to reduce waste. A shorter feed pipe between the reservoir and the distribution valve can also help reduce waste. The use of special distribution valves can also help to distribute the glue properly, thus minimizing waste.
Worker training has always been difficult in the application of any equipment or process, and dispensing is certainly no exception, especially for complex jet systems and desktop robots. One way to overcome this problem is to work with dispensing equipment suppliers to help with staff training when supplying, testing, commissioning equipment, and generating documented parameters when testing equipment to be used as guidance documents when training operators. Software upgrades can also significantly reduce the time required to train operators. Some equipment vendors have invested heavily in developing intuitive software interfaces to simplify the setup and programming of dispensing robots, thereby reducing the need for operator training.
