Dispensing, also known as gluing, adhesive application, coating, sealing, or dripping, is a process whereby adhesive, oil, or other liquids are applied, sealed, or dripped onto products to provide functions such as bonding, sealing, insulating, securing, and smoothing surfaces. This process is extensively applied and constitutes an integral aspect of automobile manufacturing processes.
Dispensing can be performed manually or with automated robots. In automobile production, automated robot dispensing is generally preferred due to high volume and pace, notwithstanding its higher costs and significant technical challenges. Automated dispensing typically relies on pneumatic control to push out adhesive within predetermined timeframes, theoretically ensuring consistent volume each time. Adjusting air pressure, timing, and selecting appropriate needle nozzles can regulate the volume of each dispensing cycle. However, various challenges may arise during actual production, posing critical technological hurdles.
Research identifies several factors deemed problematic during dispensing:
- Consistency of dispensing
- Accuracy of dispensing
- Equipment maintenance
- Increasing production pace
- Adhesive wastage
- Operator training
- Rework and repairs
- Consistency of dispensing
In small-batch production, inconsistency is a common and challenging issue. Approximately 44% of respondents indicated that due to small-batch production, manual operations are often preferred over automated robots. Consistency between each workpiece is the greatest challenge with manual methods due to personnel changes affecting consistency.
However, the use of advanced automated equipment somewhat alleviates consistency issues. Among respondents using air-powered benchtop dispensers, 37% identified consistency as a challenge. For those using pneumatic valve systems, 32% cited consistency as a challenge, while only 26% of respondents using positive-displacement dispensing systems considered it a challenge.
While improving dispensing equipment can address consistency issues, adhering to simple guidelines, such as addressing air bubble problems, can also make progress. Minimizing air bubbles in fluids before dispensing is crucial for accurate dispensing.
Dispensing Accuracy
Dispensing accuracy is another common problem. Similar to consistency, 41% of manual operation respondents and 35% of pneumatic dispensing users identified dispensing accuracy as a challenge.
When using pneumatic valve systems, such as diaphragm valves and needle valve systems, accuracy issues are less pronounced. Some manufacturers utilize advanced jetting systems, such as electronic pneumatic jet valves and piezoelectric jet valves, to significantly improve accuracy.
Advancements in pneumatic dispensing machines also contribute to improved accuracy. Software enhancements enable many machines to perform multi-point dispensing operations, accelerating production speeds.
Air bubbles in adhesives also affect dispensing accuracy. Removing air from fluids before dispensing is key to accurate dispensing.
Equipment Maintenance
Equipment maintenance has always been challenging, involving disassembly, cleaning, lubrication, and downtime maintenance. Unlike the above points, automated dispensing methods increase the difficulty of equipment maintenance.
In 2017 and 2018, 46% and 45% of respondents respectively found maintenance of positive-displacement dispensing systems to be the top challenge.
Additionally, 39% and 33% of respondents in 2017 and 2018 respectively viewed maintenance of pneumatic valve systems as a challenge.
Furthermore, 35% of respondents in 2018 found maintenance of pneumatic jet valve system equipment to be particularly difficult.
Compared to pneumatic valves and jet valve systems, more respondents consider positive-displacement dispensing systems more problematic due to their more complex components, requiring more time for disassembly and cleaning. However, the advantage of positive-displacement systems lies in their ability to provide continuous, repeatable dispensing regardless of fluid viscosity or changes over time.
The latest advancements in dispensing technology, including pneumatic valves and piezoelectric jet valves, reduce maintenance time through innovative product design. Quick-release clamps integrated into valve designs allow operators to quickly remove fluid while installing the valve into the automation system, eliminating the need for disassembly for cleaning and restoration, thus saving a significant amount of maintenance time. In fact, seamless switching between multiple fluids can be achieved with proper preparation, minimizing downtime to just a few minutes.
Accelerating Production Pace
For some component suppliers, increasing production speed is a top priority due to high demand ensuring products will sell as soon as they're produced. Any downtime equates to loss of revenue. In 2018, approximately 44% of respondents indicated that accelerating production pace was their primary challenge. Among respondents using benchtop automation systems, 43% expressed an urgent need to increase production speed.
Typically, when higher production volumes are required, using benchtop automation systems allows robots to batch dispense fluids, replacing one-to-one modes and significantly increasing production speeds.
Respondents considered production speed a pain point of automated dispensing systems, possibly because manufacturers intentionally design robot movement speeds to be slow, not exceeding safety thresholds, thus avoiding the need to enclose them in safety protection systems.
The latest benchtop dispensing robots are designed specifically to shorten dispensing cycles. These new robots use ball screw drives instead of belt drives for faster, more precise positioning. Some models can achieve position repeatability of ±0.003 millimeters.
Wastage and Training
Finally, notable concerns include adhesive wastage, operator training, rework, and scrap.
While waste of adhesive may seem insignificant, it accumulates over time, resulting in significant costs. A common method to reduce adhesive wastage is using disposable dispensing components, such as syringe barrels and pistons, designed to prevent any adhesive residue after dispensing. Some parts are specifically designed to minimize waste. Shorter feed lines between fluid reservoirs and dispensing valves can also help reduce waste. Using specialized dispensing valves can also assist in optimal adhesive distribution, minimizing wastage.
Worker training has always been a challenge in any equipment or process application, and dispensing is no exception, especially for complex jetting systems and benchtop robots. One way to overcome this is to collaborate with dispensing equipment suppliers to provide employee training during equipment supply, testing, and debugging, generating documented parameters during testing to serve as guidance for operator training. Software upgrades can also significantly reduce operator training time. Some equipment suppliers invest heavily in developing intuitive software interfaces to simplify setup and programming of dispensing robots, thus reducing the need for operator training.
