A linear actuator is a self-supporting structural system capable of reworking a circular motion generated by a motor into a linear motion alongside an axis. Serving to to produce movements such as the pushing, pulling, raising, lowering or inclination of a load.
The commonest use of actuators includes combining them with multi-axis Cartesian robot systems or utilizing them as integral components of machines.
The principle sectors:
industrial automation
servos and pick-and-place systems in production processes
meeting
packaging and palletisation
Indeed, just think of applications similar to plane, laser or plasma slicing machines, the loading and unloading of machined pieces, feeding machining centres in a production line, or moving an industrial anthropomorphic robot alongside an additional external axis so as to broaden its range of action.
All of those applications use one or more linear actuators. In response to the type of application and the performance that it must assure in terms of precision, load capacity and speed, there are various types of actuators to choose from, and it is typically the type of motion transmission that makes the difference.
There are three predominant types of motion transmission:
belt
rack and pinion
screw
How can you ensure that you select the right actuator? What variables does an industrial designer tackling a new application should take into consideration?
As is usually the case when talking about linear motion solutions, the necessary thing is to consider the issue from the best viewpoint – namely the application and, above all, the outcomes and performance you are expecting. As such, it is worth starting by considering the dynamics, stroke size and precision required.
Let’s look at these in detail.
High Dynamics
In lots of areas of commercial design, similar to packaging, for instance, the calls for made of the designer very often have to do with velocity and reducing cycle times.
It's no surprise, then, that high dynamics are commonly the starting level when defining a solution.
Belt drives are often the perfect solution when it comes to high dynamics, considering that:
they allow for accelerations of up to 50 m/s2 and speeds of as much as 5 m/s on strokes of so long as 10-12m
an X-Y-Z portal with belt-driven axes is typically capable of handling loads starting from extraordinarily small to approximately 200kg
in keeping with the type of lubrication, these systems can offer particularly long maintenance intervals, thus guaranteeing continuity of production.
Wherever high dynamics are required on strokes longer than 10-12m, actuators with rack and pinion drives are usually an excellent solution, as they allow for accelerations of as much as 10 m/s2 and speeds of up to 3.5 m/s on probably infinite strokes.
The selection of a unique type of actuator would not guarantee the same outcomes: a screw system, which is undoubtedly a lot more exact, would definitely be too sluggish and wouldn't be able to deal with such long strokes.
Lengthy Strokes
Systems created by assembling actuators within the typical X-Y-Z configurations of Cartesian robotics typically, in applications comparable to pick-and-place and feeding machining centres along production lines, have very lengthy strokes, which can even reach dozens of metres in length.
Plus, in many cases, these lengthy strokes – which normally involve the Y axis – are tasked with dealing with considerably heavy loads, typically hundreds of kilos, as well as numerous vertical Z axes which operate independently.
In these types of applications, your best option for the Y axis is certainly an actuator with a rack and pinion drive, considering that:
thanks to the inflexibleity of the rack and pinion system, they're capable of operating alongside potentially unlimited strokes, all whilst maintaining their inflexibleity, precision and efficiency
actuators with induction-hardened metal racks with inclined teeth which slide along recirculating ball bearing rails or prismatic rails with bearings are capable of dealing with loads of over one thousandkg
the option of putting in a number of carriages, every with its own motor, permits for quite a few independent vertical Z axes.
A belt system is right for strokes of up to 10-12m, whilst ball screw actuators are limited – within the case of long strokes – by their critical speed.
Positioning Repeatability
If, on the other hand, the designer is seeking maximum precision – like in applications such as the assembly of microcomponents or certain types of dealing with within the medical field, for instance – then there is only one clear selection: linear axes with ball screw drives.
Screw-driven linear actuators supply the most effective efficiency from this viewpoint, with a degree of positioning repeatability as high as ±5 μ. This efficiency can't be matched by either belt-driven or screw-pushed actuators, which each attain a maximum degree of positioning repeatability of ±0.05 mm.
The commonest use of actuators includes combining them with multi-axis Cartesian robot systems or utilizing them as integral components of machines.
The principle sectors:
industrial automation
servos and pick-and-place systems in production processes
meeting
packaging and palletisation
Indeed, just think of applications similar to plane, laser or plasma slicing machines, the loading and unloading of machined pieces, feeding machining centres in a production line, or moving an industrial anthropomorphic robot alongside an additional external axis so as to broaden its range of action.
All of those applications use one or more linear actuators. In response to the type of application and the performance that it must assure in terms of precision, load capacity and speed, there are various types of actuators to choose from, and it is typically the type of motion transmission that makes the difference.
There are three predominant types of motion transmission:
belt
rack and pinion
screw
How can you ensure that you select the right actuator? What variables does an industrial designer tackling a new application should take into consideration?
As is usually the case when talking about linear motion solutions, the necessary thing is to consider the issue from the best viewpoint – namely the application and, above all, the outcomes and performance you are expecting. As such, it is worth starting by considering the dynamics, stroke size and precision required.
Let’s look at these in detail.
High Dynamics
In lots of areas of commercial design, similar to packaging, for instance, the calls for made of the designer very often have to do with velocity and reducing cycle times.
It's no surprise, then, that high dynamics are commonly the starting level when defining a solution.
Belt drives are often the perfect solution when it comes to high dynamics, considering that:
they allow for accelerations of up to 50 m/s2 and speeds of as much as 5 m/s on strokes of so long as 10-12m
an X-Y-Z portal with belt-driven axes is typically capable of handling loads starting from extraordinarily small to approximately 200kg
in keeping with the type of lubrication, these systems can offer particularly long maintenance intervals, thus guaranteeing continuity of production.
Wherever high dynamics are required on strokes longer than 10-12m, actuators with rack and pinion drives are usually an excellent solution, as they allow for accelerations of as much as 10 m/s2 and speeds of up to 3.5 m/s on probably infinite strokes.
The selection of a unique type of actuator would not guarantee the same outcomes: a screw system, which is undoubtedly a lot more exact, would definitely be too sluggish and wouldn't be able to deal with such long strokes.
Lengthy Strokes
Systems created by assembling actuators within the typical X-Y-Z configurations of Cartesian robotics typically, in applications comparable to pick-and-place and feeding machining centres along production lines, have very lengthy strokes, which can even reach dozens of metres in length.
Plus, in many cases, these lengthy strokes – which normally involve the Y axis – are tasked with dealing with considerably heavy loads, typically hundreds of kilos, as well as numerous vertical Z axes which operate independently.
In these types of applications, your best option for the Y axis is certainly an actuator with a rack and pinion drive, considering that:
thanks to the inflexibleity of the rack and pinion system, they're capable of operating alongside potentially unlimited strokes, all whilst maintaining their inflexibleity, precision and efficiency
actuators with induction-hardened metal racks with inclined teeth which slide along recirculating ball bearing rails or prismatic rails with bearings are capable of dealing with loads of over one thousandkg
the option of putting in a number of carriages, every with its own motor, permits for quite a few independent vertical Z axes.
A belt system is right for strokes of up to 10-12m, whilst ball screw actuators are limited – within the case of long strokes – by their critical speed.
Positioning Repeatability
If, on the other hand, the designer is seeking maximum precision – like in applications such as the assembly of microcomponents or certain types of dealing with within the medical field, for instance – then there is only one clear selection: linear axes with ball screw drives.
Screw-driven linear actuators supply the most effective efficiency from this viewpoint, with a degree of positioning repeatability as high as ±5 μ. This efficiency can't be matched by either belt-driven or screw-pushed actuators, which each attain a maximum degree of positioning repeatability of ±0.05 mm.
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