The motion control solution with higher load density
Markus Brändle of Thomson discusses high load ball screws as an alternative to roller screws.
Motion engineering quiz: If you need to actuate a 500kN axial load along a 1500mm stroke, do you use roller screw or a ball screw? If you reflectively said roller screw, you may not be familiar with high load ball screws as an economical and simplified alternative. Roller screws have been promoted as the only technology of choice for handling large loads when size is a constraint. But in actuality, advances in ball screw technology make special versions viable candidates for high load applications as well, and this is important because a high load ball screw is typically less than half the cost of a comparable roller screw at equivalent performance points.
A ball screw consists of a threaded metal shaft with a nut that rides along its length as a motor rotates the shaft. The nut connects to a table, an arm or other load as determined by the industrial process that is being automated. Recirculating ball bearings packaged within the nut contact the threads and provide the load bearing path. The coefficient of friction between the mating components is very low which provides a system efficiency which is typically greater than 90%.
The load capacity of the ball screw is then a function of the ball bearing diameter, number of ball bearings, and the surface contact area. The combination of these parameters then defines the load capacity of the assembly and therefore the resultant life of the components.
For higher loads, design engineers have specified roller screws into many applications. In a roller screw, the load bearing mechanism is a set of recirculating rollers instead of balls. The rollers have more total surface contact area than balls, which increases the load carrying capacity and can also increase service life. But these benefits come at premium. Compared to the relatively simple, time-tested ball system, the roller screws require extensive upfront precision machining and more complex assembly. This contributes to the overall higher cost of the roller screw, as well as a larger footprint for final installation.
Thomson has developed a high load ball screw by implementing a unique thread form that increases load bearing capacity four to eight times over traditional ball screws. This gives the application engineer the option of deploying a ball screw in most any application that previously required a roller screw. Or, because the life of the assembly is a direct function of the load capacity, using a high load ball screw in a low load application would extend the life of the product.
Consider, an automotive equipment assembly application, which is running a load of 100kN, 24/7. Based on the standard life calculation, the product may last 3-4 months according to the fatigue failure analysis and statistical life expectancy. Implementing a high load ball screw, however, would double the load capacity and yield eight times the life. So the manager of each production unit has the option of going for higher load capacity, longer assembly life or the combination of the best of both.
Taking another example, an injection moulding application might require 400kN of force over 500mm, for which a designer might traditionally specify a roller screw. But that high force is required only for maybe the last 10mm, when the mould is being compressed. The user then is paying a premium for high load across the full stroke. By deploying a high load ball screw, though, the designer gets the needed power at the final 10mm, while additional load bearing potential factors into extended life for the product.
The table illustrates the advantage of a high load ball screw in an application that requires a minimum of 470kN of dynamic load capacity. A standard configuration ball screw is capable of providing a solution but is twice the diameter and costs 60% more. A roller screw is also capable but has a nut that is close to 50% larger at 150% the price of the comparable high load ball screw.
Thomson provides a standard range of high load ball screws up to 160mm diameter with a maximum of 1400kN dynamic load capacity, and customised ball screw assemblies according to specific application demands are available upon request. Specifying high load ball screws in applications previously relegated to roller screws can save money, extend product life or both.
Any new application will require careful analysis of load capacity, product life and cost, and in doing so, there may still be some applications well-suited to roller screws. But given new ball screw technology advances that increase ball screw load bearing capacity, it is now wise to consider Thomson high load ball screws in any application for which you might now be considering a roller screw. It could pay off significantly.
Other News from Thomson Linear Motion
Latest news about Linear acctuators
- Investing in skills and technologies proves key
- ElectroCraft expands the AxialPower family of linear actuators with the APES 17
- compact electromechanical linear actuators with embedded CANbus support and PLC capability
- High force integrated actuator reduces footprint and extends service life
- Robots get greater range with plug-and-play linear actuators
- The force awakens
- Universal torque wrench calibration
- Going beyond just servo valves for auto test labs
- Proportional solenoids just got even smaller
- High force actuators: convert from hydraulic to electric
- Considerations for selecting electric actuators for harsh environments
- Screw jacks design guide for automation
- A quick guide to selecting the best linear motion product
- Igus expands leadscrew range with iglidur E7 nuts
- Micro gripper allows fragile part handling to 2.5g force
- Actuators keep Sperry Rail on track
- Articulate gantries keep axle production moving
- Linear actuator drive choice is a precise balancing act
- Actuator is adaptable to a range of applications
- Reliance launches new actuators catalogue
- Lifting Cathedral’s dais to new heights
- Redesigned linear stages improve your process by up to 98%
- LG Motion delivers a perfect soft landing with moving coil actuators from SMAC
- New ideas in linear motion
- How to specify simple, reliable and adaptable screw jacks
- Modular design for electric actuators
- Zimmer clamping and breaking MBPS from Moore International
- New high load precision linear module from SKF
- New recirculating units offer unlimited stroke
- XY piezo nanopositioning stages with 50x50mm aperture
- Igus drylin ZLW for linear robotic applications
- Electric cylinders offer high power and speed
- Actuator switch delivers 89% energy savings
- Electromechanical joining module
- IP rated products from SMAC-MCA
- Haptic accelerator pedals improved
- Discovering the benefits of electromechanical actuation
- How to specify simple, reliable screw jacks
- Electric versus pneumatics
- Planetary screw drive offers high load carrying capacity and high power density
- Electric versus pneumatic
- Guideways, stages and ballscrews, plus accessories
- Miniature actuation solutions for Steeper's bebionic hand
- Trends in specifications for industrial linear actuators
- Inkoma KSH bevel gear high speed screw jacks from Francis and Francis
- Microsite showcases benefits of electric linear actuators in off-highway applications
- Electric throttle control for mechanical diesel engines
- Fast actuator delivery for machine builders
- Servo motor driven ballscrew key to car seat test system
- Linear drive technology aids PCB production throughput
- Back to basics on linear motion systems
- Warner Linear supplies actuators for all-terrain vehicles
- HepcoMotion linear actuators boost safety at packaging plant
- Integrated XY ball-screw stage for cost-sensitive planar performance
- Linear actuators
- Intelligent stepper motor linear stages
- Moore International at Southern Manufacturing 2014
- Eight tonne load driven into oven
- Self-lubricating and compact, drylin E offers a complete drive solution, with axis and motor
- New Generation of drylin Linear Axes for food and beverage applications
- Electric cylinders deliver control and flexibility
- High acceleration, high load and smooth running
- Linear solutions for heavier loads
- Low friction positioning and transportation
- Powerful, precise option for linear positioning tasks
- Robust and reliable electric linear actuation
- Screw drives for machine building and automation
- Simulator improves race cars and driver training
- Smooth, accurate, linear positioning systems
- Schaeffler extends ballscrew drives to include new rolled version
- Linear actuation for hovercraft steering
- Moore International to distribute Schneeberger
- Selecting lead screws
- Fully integrated linear actuator and rolling bearing units designed for solar tracking systems
- Sun seekers
- The future belongs to electric actuation
- High-speed axis features roller bearings for higher performance
- Optimised motion series provides cost-effective motion control
- Cost-effective linear motion for a wide range of applications
- Bomb disposal robot gets extra lift with actuator
- Raising the stakes
- igus linear drive modules for extreme conditions
- Miniature linear actuator offers stroke lengths of up to 250mm
- Linear actuators ensure precise positioning of sheet metal parts for transformer cores
- Actuators compatible with profile system
- Linear actuator speeds up pick and place processes
- Screw jacks for hygiene conscious tasks
- Servo press module equipped with wireless telemetry for clean rooms
- Simple solution found for heavy duty linear actuator
- Heavy-duty linear axis with belt drive or ball screw
- Linear actuators enable faster delivery of prescription medication to patients
- Adapter kit enables linear bearing systems to be built easily
- Small, lightweight and lubricant-free system for positioning small loads
- New electro hydrostatic design concept unveiled
- Welding guns rely on ballscrews
- Renewable Energy in Motion
- Back to basics on ball screws
- Electric cylinders
- Folded over motorised linear rail system
- Servo actuators provide a boost for machine productivity
- NSK achieves 40% cost reduction for welding gun manufacturer
- Linear motion technology
- Maximum precision from spindle drives
- Penny and Giles integrates Mechetronics into its controls division
- Lubricant-free linear drive fully assembled with NEMA motor
- Electric alternative to screw or belt drives
- Novel bi-parting drive cuts the cost of machine automation
- Linear motion: myth and reality
- Rack and pinion drive system
- Roof lift improves composting
- Linear actuators bring greater flexibility to automation
- Cost effective alternative to pneumatic actuators
- Screw jacks
- Compact, precise external actuator
- Greater choice needed as Britain automates
- Lightweight face tests respirator seals
- Linear actuation for Advanced Gun System for the US Navy
- Medical leadscrews in miniature sizes
- Short stroke electric cylinder uses tubular linear motor
- Compact actuator delivers reliability for film winding
- High performance in a small package
- Heason Technology is appointed Premier Partner for Danaher Motion's Thomson brand
- Power Jacks provides the lift for aero engine transport
- All-in-one motion package
- Performance cylinders based on innovative tubular linear motor
- Stainless steel linear motor
- The advantage of large journal at rolled screw cost
- Festo enters low-cost electric actuator market
- All-in-one actuator package is an easy to specify option
- From light duties to the most rugged
- Guide ball bushing for miniature sizes
- High speed linear motion
- Linear actuators with embedded force sensors
- Linear motion package suits clean room tasks
- Screw jacks weigh up the universe
- Vacuum-through shaft actuator eliminates common dust problems
- Belt driven actuator is a really fast mover
- Linear motion products
- Power Jacks Helps Wimbledon Play On
- Safe work access for nuclear containers
- Actuators drive ground printing machines
- Ballscrews take to the sky
- Driven to provide greater capacity
- Increased safety and longer life
- Actuators ideal where space is tight
- All-in-one linear actuator technology is on a roll
- Linear actuator offers higher force
- Rack actuator offers precision and efficiency
- Actuators reduce package size and cost
- Direct drive modules increase throughput
- Linear drives range boosts performance
- Actuators go stainless
- Corrosion-free screw jacks
- Electrics oust pneumatics
- Left handed and right handed lead screws
- Linear actuators now have inbuilt force measuring option
- Mechatronic assemblies integrate intelligence
- Push or pull the heaviest of loads
- Radical new option for linear motion
- Modularising machine design and build
- Actuation systems
- A more productive plant
- Drive systems
- Electromechanical actuators prove a good fit for joining
- Off the shelf connectors for parallel motion
- Mechatronic assistance tidal simulation project
- Opening doors for neutrons
- Precision three-in-one servo actuators
- Should you build or buy?
- Telescopic pillars suit medical tables
- Virtually unlimited lift in a space saving package
- The myths of converting to electric actuators debunked
- Belt actuator combines accuracy and durability
- Automation made simple with linear motion technology
