17 Work Performers of Pneumatic Systems Learning Objectives

17 Work Performers of Pneumatic Systems

Learning Objectives • Describe the construction features of basic pneumatic linear and rotary actuators. • Compare the design and operation of pneumatic cylinders. • Compare the design and operation of pneumatic motors. Parker Hannifin Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Learning Objectives • Explain the performance characteristics used to rate the operation of pneumatic motors. • Describe the basic design and operation of specialized pneumatic tools commonly used in consumer and industrial applications. Atlas Copco Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Learning Objectives • Size pneumatic cylinders and motors to meet the force and speed requirements of a basic work application. • Interpret manufacturer specifications for basic, pneumatic cylinders, motors, and power tools. Josef Bosak/Shuttterstock Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Pneumatic Cylinders • Convert energy in compressed air to linear force and movement • Force generated determined by cylinder piston area and system air pressure • Rate of movement determined by volume of actuator chamber per inch of stroke and amount of air allowed in actuator Parker Hannifin Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Basic Cylinder • Piston and piston rod assembly operating within barrel • One end of barrel closed • Open end allows piston rod to extend outside component • Seals prevent leakage to exterior of cylinder • Ports on either end allow air to be forced into and vented from sealed chambers • Basic structure similar to hydraulic cylinders IMI Norgren, Inc. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Construction Materials • Must be able to withstand harsh operating conditions • Increase corrosion resistance by using resistant materials such as brass or chromium-plated steel • Most cylinders use resilient materials for piston seals • Some manufacturers produce nonlubricated cylinders IMI Norgren, Inc. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Classification of Cylinders • Single- or double-acting • Single-acting generate force in only one direction • Double-acting generate force during both extension and retraction • Difference in effective area of each side of piston and rod assembly results in different extension and retraction force outputs IMI Norgren, Inc. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Classification of Cylinders • Head and cap attached to barrel using methods similar to ones used for hydraulic cylinders • Threads or snap rings to attach head and cap to barrel Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Classification of Cylinders • Head and cap can be permanently attached to barrel • Lower operating pressure allows metal rolling technique • Improved designs allow extended service before required replacement Parker Hannifin Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Sizing a Pneumatic Cylinder • Two factors to consider when selecting cylinder: • Required force output • Air consumption needed to provide desired cycle-operating rate • Factors ensure actuator will provide desired performance Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Required Force Output • Determined by system air pressure and effective area of cylinder piston Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Determining Air Consumption • Determined in cubic feet of free atmospheric air per minute • Air leaks and variations in actual volume of cylinder air chambers can cause inaccuracies Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Cylinder Manufacturer Specifications • Manufacturers provide considerable information on: • Construction materials • Available sizes • Pressure ratings • Specifications regarding cylinder features Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Cylinder Manufacturer Specifications • Details include data and illustrations covering factors such as: • Duty service and pressure ratings • Construction type • Bore and port fitting sizes • Piston rod diameter • Stroke length • Mounting style • Cushions • Rod-end configuration Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Pneumatic Rotary Motors • Pneumatic motor converts energy in compressed air into torque and rotary movement • Torque generated depends on area of driving mechanism and system air pressure • Speed determined by volume of internal motor chambers and amount of air allowed in component Atlas Copco Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Basic Rotary Motor Design • Need internal chambers that can vary size to allow air to move through motor • Motor constructed using housing, rotary internal parts, and power output shaft component groups • Speed determined by displacement of motor chambers and volume of air allowed to pass through • Torque depends on internal structure of motor and air pressure available to motor circuit Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Rotary Motor Operation Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Rotary Motor Design, Construction, and Operation • Several different designs available • Ranges from small, portable hand tools to high-horsepower industrial applications • Each design depends on compressed air as source of air volume and pressure needed for operation Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Vane Motors • Most common rotary air motor design • Typically produced with three or more vanes • Seal between tips of vanes and walls of motor body maintained over full range of motor speeds and loads • Springs or air pressure to maintain seal • Available in variety of sizes and as lubricated or nonlubricated Atlas Copco Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Piston Motors • Desirable in applications requiring high power output • Available in both axial- and radial-piston designs • Axial-piston motors have cylinders and pistons centerlines parallel with output shaft centerline • Radial-piston motors have cylinders and pistons perpendicular to output shaft centerline • Range from less than 1 horsepower to over 50 horsepower • Nonlubricated or lubricated Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Turbine Motors • High-speed air directed onto turbine wheel produces rotary motion • Nozzle converts potential energy of static, high-pressure air into kinetic energy in highspeed air • Limited in application due to high output speeds • Most common for small, high-speed grinding operations Atlas Copco Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Selecting a Rotary Pneumatic Motor • Manufacturers supply tables with details of motor performance • Maximum speed, power output, torque, and air consumption • Graphs to identify these over range of operating speeds • Loads that will be encountered must be carefully analyzed Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Pneumatic Reciprocating Motors • Produce linear motion that completes tasks with percussive or nonpercussive techniques to transfer energy • Percussive devices use multiple impacts of cylinder piston • Nonpercussive devices use repeated, reciprocating movement Atlas Copco Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Basic Reciprocating Motor Design • Percussive reciprocating motor is a cylinder closed at one end • Opposite end fitted with base of working tool or anvil • Cylinder divided into two chambers by free-floating piston • Incoming air moves piston toward tool base or anvil, strikes base or anvil, and transfers energy Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Basic Reciprocating Motor Design • Nonpercussive reciprocating motor has rod attached to cylinder piston • External rod end attached to component requiring reciprocating movement • Valve or cylinder ports provide control needed for constant reciprocating action Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Applications for Reciprocating Motors • Paving breakers, or jackhammers, used in street maintenance and at building demolition sites • Scaling hammers remove flux and spatter from welds in fabricated products • Chipping hammers perform diverse tasks, such as cleaning foundry castings or roughing concrete surface Atlas Copco Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Applications for Reciprocating Motors • Riveting hammers form head of rivets used in airplane construction • Tampers and rammers compact sand in foundry molds and dirt at construction sites Badger Iron Works, Inc. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Other Pneumatic-Powered Functions and Equipment • Compressed air used in wide variety of equipment and processes • Many not visible to general public • Designed or modified to: • Reduce costs • Allow smaller operations • Allow consumers to use techniques formerly restricted to major manufacturers Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Process Functions • Spraying • Painting most recognized operation • Application of agricultural chemicals for weed and insect control • Drying cars at local car wash • Concentration of materials in chemical producing industries USDA Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Process Functions • Material agitation prevents settling of solids or maintains uniform distribution of materials in mixtures • Compressed air can be directly used, such as in sewage treatment • Material transfer expedites movement of liquid, powder, or granular materials • Food processors and cement production • Compressed air for unloading and loading railroad cars and trucks Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Other Mechanical Equipment • Air nozzles convert potential energy of compressed air into kinetic energy of rapidly moving air • Convergent or convergent-divergent design • Varying length of curved portion provides means to control velocity and pressure of air as it passes through nozzle Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Other Mechanical Equipment • Blowguns used in many shops for cleaning • Eye protection needed • Bleed-off prevents risk of air accidentally injecting into skin Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Caution • Never point a blowgun at anyone • Capable of causing serious injuries, especially to the eyes and ears IMI Norgren, Inc. Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Other Mechanical Equipment • Impact wrenches quicken process of tightening and removing nuts and bolts • Compressed air provides rapid acceleration of impact mechanism • Commonly used in service and manufacturing operations • Available in a range of sizes • Nutsetters reduce assembly times in industrial assembly lines Chicago Pneumatic Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Other Mechanical Equipment • Nail drivers drive fasteners in building construction, furniture assembly, and other applications • Used by small contractors, major home developers, and manufacturing operations • Staples, small brads, large-head shingle nails, and nails 2″ or longer • Safety mechanism to reduce possibility of fasteners becoming projectiles Goodheart-Willcox Publisher Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Other Mechanical Equipment • Pneumatic rock drills make rock cuts in quarries, mines, and highway construction • Bore holes allow placement of explosive charges to break rock • Available in a number of sizes • Hand tools or major pieces of equipment in large drilling operations Atlas Copco Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.

Other Mechanical Equipment • Grippers used by robots to place and remove parts in machining, assembly, or other operation • Some allow adjustment of opening and closing of jaw and force applied to handled part • Structure must provide accuracy for consistent jaw clearance and gripping force Josef Bosak/Shuttterstock Copyright Goodheart-Willcox Co. , Inc. May not be posted to a publicly accessible website.