The excerpts below were taken from NFPA's publication, Your Guide to Cost Reduction through Pneumatics Automation. Through the use of case studies and illustrations, this guide explains how pneumatics automation could reduce manufacturing costs with a minimum of investment and complexity.
We encourage you to learn more about how pneumatics can help you by reviewing the following selections:
You Already are a Master of Pneumatics Automation
How to Identify Cost Reduction Opportunities
Pneumatics Automation as a Cost Reduction Tool
How to Carry Out Your Own Pneumatics Automation Project
Pneumatics Automation Trouble-Shooting Guide
Fluid Power Applications - Pneumatics Automation at Work*
Fluid Power Applications - Electropneumatics* (From Your Guide to the Electronic Control of Fluid Power, copyright © 1992, by the National Fluid Power Association.
*To view the applications you will need Adobe Acrobat Reader software. The software is free, go to Adobe's web site to download the reader.
*Copyright 1990 by the National Fluid Power Association. All rights reserved. The applications and components described or pictured here are illustrative only. Depiction or description of any product or component does not constitute, indicate or imply a recommendation or endorsement of any sort with respect to any system, products or components. Information and illustrations in this booklet, and excerpted at this web site, do not constitute or indicate a warranty, express or implied, including but not limited to a warranty or representation as to quality, merchantability or fitness for a particular use or purpose of any system, product or component.
Have you ever. . .
The above tasks contain most of the skills needed to successfully complete a simple pneumatics automation project. Simple pneumatics automation differs from large-scale, integrated automation even though it utilizes many of the same components and techniques.
Integrated automation projects often involve centrally-controlled, multi-station manufacturing processes.
These complex assembly projects can cost hundreds of thousands of dollars and take months or years to complete. Simple pneumatics automation projects can be completed with far fewer resources expended since they are usually focused upon mechanizing a single task. If necessary, they can later be incorporated into an assembly of machines.
Simple pneumatics automation harnesses the power of today's low-cost, understandable electronic, electrical and mechanical technologies. It utilizes standard components such as actuators, valves, sensors, programmable controllers, grippers, air motors and other similar devices which are designed to be readily assembled into a working automated application.
Of course as you automate with pneumatics, be sure to read and observe all use and safety related instructions and recommendations of the manufacturer and supplier involved. Equipment should be installed and used in accordance with the manufacturers' and suppliers' instructions. Take the time to properly train your employees in the correct and safe method of operation of automated equipment. A safe work environment is essential for employee well-being and satisfaction, and makes good business sense.
Reducing costs can be easy when you take the process in steps, working on one project at a time. Where do you start? Here are some clues. Take a walk through your plant and look for these opportunities to save yourself some time and money:
An examination of your cost-accounting data will reveal opportunities that might be less obvious, but just as significant. Check the time for each operation on each part, looking for bottlenecks in any process. Let your experience tell you which times seem unreasonable and which methods seem inefficient. Then consider the approaches offered in this guide.
Your company is only as strong as its ability to compete. By learning how to reduce the cost of producing your products, you will become an even more valuable member of your manufacturing team and your company will become an efficient and competitive producer.
Once you understand how to use pneumatics automation, your dependence on the large capital expenditures needed to increase efficiency should decline. Because of the low cost of pneumatics automation, even job runs in the hundreds of pieces can be automated with excellent results, not only financially, but in efficiencies gained.
Now for some specifics. Pneumatics refers to an interrelated group of automation building blocks that use compressed air as a power source. You can use these components to assemble your own economical, cost-saving devices. Choose from devices including:
Automation with pneumatics can save you money. We have identified six applications in this guide, but there are many more. Just to get you started, we'll show you how pneumatics will enable your manufactured parts to be . . .
In order to construct the best pneumatics automation project; here are the steps you should follow:
Determine the environment.
This includes the availability of a constant supply of compressed air operating at an acceptable pressure level (usually around 90 pounds per square inch). Suitable electrical power sources will usually also be required.
Record the operating temperature and moisture level limits to determine if special types of materials, shielding or sealing will be required and that the components you choose will operate properly under your specific conditions. If the application will receive parts from, or transfer parts to, another assembly station, conveyor line, pallet, parts bin or similar conveyance, establish minimum and maximum rates for parts acceptance or transfer. If your application must interact with another machine (such as switching it on or off), check to see what the control requirements are for that machine in terms of electrical load, cycle rate and availability of connections.
Study necessary motion.
Generally define the type of motions necessary to perform the task to be automated by studying the manual processes currently being used. Look for inefficiencies in the manual system, and try not to reproduce them through automated movement. From the point of delivery to the automated station, trace the path of the part, noting where it must be staged, clamped, turned or otherwise manipulated. Try to determine the most direct path for material movement which can be executed by moving the part from one point to another, usually within a single plane.
Routing the part to its ultimate destination usually requires a series of these "point-to-point" moves, since tracing an exact angular path across two planes may require special guides or fixtures. Think of straight-line moves: up, down, over, in or out, and you will most effectively utilize simple pneumatics automation.
Examine the part.
Determining the size, weight, composition, shape and surface type of the part to be worked is essential. These factors dictate the type of devices, the mounting approach, the tooling used to grip the part during movement, and the load capacities of the components selected.
If a relatively heavy (over one pound) part must be moved horizontally with any degree of accuracy, selection of heavier duty slides versus simple cylinders may be in order. Part surface type and material composition will determine use of gripping device type, including angular versus parallel jaw grippers, suction cups or other holding means. Part shape will determine the type of tooling which will be required to make direct contact. This tooling is almost always customized due to the diversity of part sizes and shapes. On heavier parts, some type of deceleration device may be needed when cycle speeds are fast.
Determine the part quantities, production speed and accuracy.
If the application is to be used only for a limited run of parts and will then be dismantled, it will endure lighter duty components and less permanent mounting approaches. Production speed will determine compressed air pressure ratings, air flow, parts routing and the need for alternative actuation power sources (such as use of electric devices like stepper and servo motors). If a part must be moved very quickly, the accuracy with which it can be moved in a single segment may be lessened.
Accuracy requirements will also determine the need for guide fixtures and jigs, use of non-rotating versus rotating cylinders and sensor selection. Sensors, for instance, are used to determine whether a part has been successfully picked up or moved to a certain point. (If less sensing accuracy is required, a proximity switch may be employed which may sense to within plus or minus .125 of an inch. For increased accuracy, an electronic set point module may be used with a variable output sensor which can achieve sensing accuracies to within .007 of an inch.)
Measure the application and select the components.
Once the previous requirements have been established, accurate measurements must be made to determine the starting and stopping points for each motion to be effected. This usually means first drawing a dimensional model on paper. If you are adapting the automation around existing machinery, accurate measurements must be obtained or made for entry and exit points to and from these machines. The distances which are to be traveled by the part must also be accurately established and recorded on your dimensional model or layout. Using these dimensions, previously established tolerances, life cycle requirements and cycle time, the proper components must be selected.
It is important to size the components correctly. Buying a heavier-than-needed component may result in less accuracy, slower movement and longer payback periods. Buying a lighter duty component can result in premature wear or improper functioning of the system. Selection of controlling devices, typically programmable controllers, should be made after evaluating the number of switching and sensing operations to be performed and their sequence. Ease of set-up, use and future expansion capacity should also be considered when selecting a programmable controller.
Make the fixtures, mount and assemble.
Most simple automation component systems provide a variety of standard transition plates, mounting brackets, stands, stanchions and other rigging devices. As mentioned, special tooling is usually required to pick up and hold the part to be worked. However, most tooling in these situations can be constructed from flat stock, roll stock or other standard material shapes. Electrical connections and control mounting locations will have to be determined and executed, along with safety cut-off switches, guards and other safety barriers.
Debug and calibrate.
Most automation applications will require some degree of debugging and calibration. These operations typically take the form of fine tuning the programmable controller sequencing and timing, or adjusting air flow rates and physical stops for the actuators used in the system. Some repositioning of various items may be required to increase efficiencies.
Safety First
All equipment and components, pneumatic or otherwise, should be installed and operated at all times in accordance with the instructions and recommendations of the manufacturer and supplier. Employees should be properly trained in the appropriate and safe use of equipment. A safe working environment is essential for employee well-being and satisfaction, and makes good business sense.
Solution: Irregular rod motion could be caused by . . .
Solution: Install a cushioning device. Springs, rubber bumpers, cylinder cushions, deceleration valves, dashpots, feed controls, hydraulic checks, control circuits, industrial shock absorbers and linear decelerators are all devices that offer various forms of cushioning or stroke control.
Solution: Vacuum ejector-style pumps of the single chamber type often emit high sound levels. Special mufflers are available which can reduce this noise level. The vacuum pump, if a mechanical type, should be lubricated regularly.
Solution: The cylinder may be carrying too much weight. Consider replacing it with a linear slide whose guide shafts and bearings are designed to bear heavier loads which are being moved horizontally.
Solution: Electrical noise may be interfering with sensor operation. Use a different power supply for the programmable controller and sensors than is being used to drive heavier duty components (motors, pumps, electrodes, etc.). If this is not possible, investigate resistor-capacitor networks or clamping diodes to condition the current against spikes or electrical noise.
Solution: The piston rod diameter was probably too small for the amount of thrust and stroke length to which it was subjected. The cylinder sizing calculations should be rechecked and the cylinder should be replaced with one containing the proper size piston rod.
Solution: Check the following:
Solution: Solenoid electromagnet coil burnout could be caused by a voltage mismatch, with either too high or too low a voltage being supplied, or a frequency mismatch. Voltage ranges should typically fall within the +/- 10 percent range. On double solenoid valves which are yoked to the same valve spool, energizing both solenoids at the same time can also cause coil burnout. Cycling a solenoid valve too quickly can result in coil failure. Temperature extremes can also promote coil failure, with high temperatures causing a breakdown in coil wire insulation and cold temperatures causing valve parts to distort and drag. Dirt, oil, moisture or other foreign matter invading the valve may cause it to stick or score, again causing coil burnout. In all situations, correction of the abnormal state should be made and the valve should be repaired or replaced.
Solution: Leakage can occur from worn or incorrectly installed actuator and valve seals; worn or incorrectly installed fittings, connectors or hose; or corroded or damaged air storage tanks and supply lines. External leaks can be isolated by listening for the sounds of air escaping, by applying soapy water or similar high surface tension substances to suspected leak areas, by unhooking suspected leaky valves or actuators and operating them independently or by measuring the amount of time portions of the systems take to depressurize.
