New Technology Improves Precision and Minimizes Waste in Coating Operations
Uniform application of coatings is critical in a wide range of operations. It is often the deciding factor during QC/QA inspections.
Over-application, under-application or uneven application of coatings can result in high scrap rates and costly rework.
Another critical aspect in coating operations is precision. Applying the proper amount of coating on the target without overspray can be extremely difficult. Over-application not only wastes costly coatings but it also often creates a mess on conveyors and surrounding production areas. The result is an increase in maintenance time and a decrease in production time.
Pulse-width-modulated (PWM) flow control is a new technology that effectively solves these issues.
PWM flow control involves switching an electrically-actuated spray nozzle on and off very quickly in order to control the flow rate of the nozzle. This cycling takes place so quickly that the flow often appears to be constant and the coverage remains reasonably uniform.
Controlling flow rate by adjusting duty cycle of an electric nozzle at a constant pressure is the key to uniform coating and the elimination of quality problems. Typically, flow rate is increased by increasing pressure. However, increasing pressure results in dramatic changes to the spray angle and drop size. With PWM flow control, flow rate
from a single nozzle can be varied without changing pressure. Spray angle and drop size remain unchanged and uniform application of coatings is ensured.
Other benefits of PWM flow control include:
- Decreased fluid consumption. Improving transfer efficiency and controlling flow rate more precisely reduce costly chemical usage.
- Reduced clogging. Low flows can be maintained even with large spray orifices.
- Reduced misting. Generating low flows using larger orifices at lower pressures reduces or eliminates the misting that often results at higher pressures. The risk of worker inhalation of chemicals is reduced and overspray is minimized or eliminated.
- Spraying food ingredients onto products or into trays.
- Spraying flavors or oils onto bread and pastries.
- Spraying oil to improve mold release.
- Applying adhesive to tire treads before re-treading.
- Applying a uniform coating of silicone across a conveyor to prevent sticking.
- Spraying water to act as a catalyst for glue in door manufacturing.
- Spraying water on a cellulose strip to reduce electrostatic charges during manufacturing.
- Applying a thin coating of oil on the strip during the aluminum coil finishing process to prevent corrosion.
- Applying a thin coating of zinc citrate on flat glass to prevent corrosion and discoloration.
- Precisely applying moisture to fabric to facilitate dyeing and finishing operations.
In summary, the use of PWM flow control enables manufacturers to make significant gains in product quality by eliminating inconsistent application of coatings. It also helps eliminate waste of costly coatings and improve workplace safety. The technology is gaining rapid global acceptance in a wide range of industries.
New Basic Spray Systems with Built-In Spray Control Provide Fast ROI
Automating conveyor-based operations involving spray technology can result in significant efficiency gains and cost reductions. This is true even in relatively simple operations where the idea of automation was atone time cost-prohibitive. Recent technology advancements and the introduction of new low-cost basic spray systems with built-in spray control have enabled cost-effective automation of a wide range of cleaning, coating, cooling, moisturizing and oiling operations.
These new spray systems are extremely easy-to-use. They are ready to use right out of the box and operators can have them up and running in minutes. In addition, the systems are very compact – just over 2 ft tall – and can be easily integrated into the plant floor.
Designed to control automatic spray nozzles, these systems offer many benefits:
- Precise and accurate placement of the sprayed liquid on the target with minimal waste.
- Uniform application of the sprayed liquid. Automated air and liquid controls ensure proper flow and drop size.
- When used with electrically-actuated spray nozzles, PWM flow control can be achieved to increase operating flexibility and vary flow rate without adjusting pressure.
- Operators previously tasked with spray system operation and monitoring can be deployed to other duties.
The savings these systems bring to most operations add up quickly and the ROI is swift. Here are two examples:
- Oil was being dripped from a trough onto a product on a conveyor. Too much oil was being applied and the surrounding area was covered in oil, creating safety and maintenance issues. A simple automated spray system equipped with two automatic nozzles is now used to apply the oil on the product. Oil use has decreased by 40% and maintenance time has been reduced significantly. The cost of the system was recouped in less than two months and the manufacturer is saving approximately $32,000 per year on oil.
- A release agent was being sprayed on a conveyor by nozzles mounted on an oscillating arm. The release agent wasn’t being applied evenly across the width of the conveyor. As a result, products were sticking to the conveyor and the line was frequently stopped for unscheduled maintenance. A spray system with six automatic nozzles mounted on a spray header is now being used to apply a uniform coating of the release agent on the conveyor. If operating conditions such as line speed change, the spray controller can be used to quickly adjust flow rate. The manufacturer is saving $50,000 annually by reducing release agent use and eliminating cleaning downtime and the associated expense.The cost of the system was recovered in seven weeks.
In summary, simple spray systems with built-in spray control can help manufacturers solve a wide range of production problems and significantly reduce operating costs. The initial investment required for the system is usually moderate and the payback is fast. Additional savings are typically realized long after the original investment is recouped.
New Approach to Tank Cleaning Equipment Selection and Performance Optimization
Automated tank cleaning has become widely accepted as processors search for ways to ensure tank cleanliness, lower operating costs and reduce cleaning time so tanks may be returned to service more quickly. Equipment options include spray balls and nozzles, motorized tank cleaners and fluid-driven tank cleaning machines. Choosing the best tank cleaning equipment can be challenging for many manufacturers due to the number of products available and the fact that performance is highly dependent on operating conditions.
Tank cleaning equipment suppliers have historically provided impact data to help guide product selection decisions. Impact level is a good indicator of the cleaning force of a tank cleaner. However, relying only on impact data to make a product selection can be risky. Here’s why:
- Impact data based on theoretical calculations will always yield a value higher than the actual impact value. That is because theoretical calculations are based on 100% nozzle efficiency – which isn’t possible. All nozzles will have at least a slight drop in efficiency when used.
- Impact data collected using specialized equipment in a spray lab is only applicable to the operating conditions used during testing. Actual impact will vary based on operating pressure, flow rate, rotational speed, tank size and more.
A new way to determine tank cleaner performance has been introduced recently. This new approach involves calculating a Cleaning Power Factor (CPF). CPF is based on an analysis of a variety of factors and specific operating conditions. CPF is then used to compare products and determine which is best for a particular operation.
- In new applications, using CPF is an easy way to compare the performance of different types of nozzles and tank cleaners when cleaning a tank of a certain size at specific pressures and flow rates.
- CPF can also play an important role during scale up. Let’s say a manufacturer is using rotary tank cleaning nozzles with a CPF of 42 to remove paint from 10 ft diameter tanks. New 30 ft diameter paint tanks are then added to the operation. The rotary tank cleaning nozzles being used to clean the smaller tanks are not capable of cleaning the larger tanks. However, equipped with the knowledge that a tank cleaner with a CPF of 42 will provide effective cleaning, the manufacturer can quickly identify a different tank cleaning product that will provide comparable performance.
- CPF can also play a role in tank cleaning optimization. Here’s an example. A motorized tank cleaner operating at 500 psi with a flow rate of 20 gpm is effectively removing a very sticky residue from tanks that are 20 ft tall and 10 ft in diameter. Cleaning time is 90 minutes consisting of six, 15 minute cycles. However, the manufacturer needs to increase production and wants to minimize the amount of time tanks are out of service for cleaning. CPF can be used to identify a comparable product that can achieve the required level of cleaning but in less time. In this case, the solution is a fluid-driven tank cleaner operating at 100 psi and a flow rate of 100 gpm. CPF of the fluid-driven tank cleaner is twice as high as the motor-driven unit and cleaning time can be reduced from 90 minutes to 15 minutes.
In summary, the use of CPF is a more sophisticated approach to tank cleaning equipment selection and performance optimization. CPF provides purchasers with better information about how a tank cleaner will perform in their operating environment, speeds the selection and evaluation process and expedites finding a product solution that can achieve specific tank cleaning objectives such as reducing cleaning time and fluid consumption.