Some of the surest, time-tested methods of linear actuation are screw drives. Whether lead- or ball- or roller screws, screw actuation remains a large part of the linear actuation equation, thanks to their reliability, accuracy, and relative simplicity of operation.
Recently screw drive developments have included advances in materials as well as manufacturing methods leading to enhanced performance in terms of greater load densities and higher load capacities. This, coupled with more integrated design offerings has meant that screw drives are finding their way into newer applications in a diverse array of settings. Screw manufacturers are seeing marked upticks in business in certain industries such as robotics and 3D printing among others, as some of the top screw manufacturers told us.
As far as screw technology goes, there is an ongoing shift in preferences regarding ball-screw standards. “The traditional ‘Saginaw’ style ball screws that we are all familiar with are still popular in the U.S., but the trend over the past several years has been toward the ISO standard metric ball nut body styles,” notes Ron Giovannone, Director for Application Engineering & Sales Support with Nook Industries. “I expect this trend to continue over the coming decade,” adds Giovannone.
When it comes to applications for screws, manufacturers have seen increased activity in some industries. For instance, Jeremy Gong, Area Sales Director for Thomson Industries, Inc., says that throughout 2021 Thomson saw increased interest and demand “predominantly driven by shortages and lengthening lead times across the board. This was a mix of customers trying to meet existing demand as well as the pursuit of safety stock at all levels.” As for industries and applications that saw growth, Gong adds that “there has been increased interest in automation, likely driven by shortages in labor throughout the U.S. Specifically, factory automation has played a large part in our precision ball screw products. The medical space also saw increased interest in our miniature guide offerings as well as our stepper motor linear actuators to be used in desktop analysis applications.”
Its’ no secret that the coronavirus pandemic has had an impact on virtually every industry in some way. Perhaps most notably are supply chain issues across the industrial sector.
“In the initial stages of these challenging market dynamics, end users and integrators adapted by placing a heavier burden on their own inventories,” notes Saurabh Khetan, Product Line Manager for Lead Screws with Thomson Industries. “This was coupled with attempts to stay ahead of shortages by placing POs with higher-than-normal volumes to ‘get it into the system’ or POs with releases far into the future. They did so in an attempt to stave off negatively impacting their own customers” adds Khetan.
However, Khetan notes that as supply chain disruptions persisted, “there has been increased acceptance by end users and integrators as well as their own customers of these challenges being here to stay for at least the foreseeable future. We have also seen evidence of end users shopping around to other suppliers and delaying new generation launches of existing programs.”
Screw protection for robotic 3D printers
Some applications can not only call for new screw designs but also redesigns of support structures and other ancillary screw components such as bellows covers and cable carriers. For instance, take robotic 3D printing systems.
The motion and protection company Dynatect has seen a surge in demand for dynamic protection components used on 3D printers large enough to create full-scale cars or even homes. There are many new manufacturers in this space, with mechanical structures at unprecedented scale. Specifically in printing homes, these large-scale printers are referred to as “factory in the field”, given their portability from location to location. Beyond printing in concrete these “factories in the field” include cutting out of windows and doors, painting, and scanning for quality verification. To accomplish this, large-scale 3D printers merge the best features of printing, robotics, and machine tooling – combined with being used outdoors like construction equipment.
These robotic 3D printing systems often use large (2 ft x 15 ft) spiral-column lifting mechanism to change the height of the printing assembly. These lifting columns have multiple bands of intertwining stainless steel threads which are exposed to process generated debris like cement grit, window cutting dust, and paint splatter. Protecting these precision lifting columns is critical for repeated performance and typically are covered by bellows. With ten different bellows manufacturing capabilities from sewn to dip-molded to vulcanized, Dynatect can offer the best bellows construction method to optimize retracted/expanded ratio for full motion, durability, and price. This construction is matched with MIL-SPEC materials specifically for harsh outdoor environments including UV exposure, outdoor weather, and process generated debris.
Robotic 3D printing systems are fed by a collection of moving power and control conductors, pneumatic or hydraulic hoses, and tubing with deposition material like cement or paint. Cable and hose wear can be one of the first things to cause downtime on a robotic application. To protect these cables and hoses, Dynatect has engineered a family of cable carriers that are optimized for outdoor dynamic industrial applications. In 3D printing applications where speed or weight is an offsetting factor, Dynatect also provides plastic cable carrier in a wide variety of cavity sizes and mounting configurations. These are also available with a wide variety of long-travel support options including a hybrid cable carrier combining the best attributes of metal and plastic.
For large-format 3D printers used for generating full size structures like cars and other intricate models, they are even more dependent on keeping dust out of the printing area along with maintaining a stable temperature to maximize uniform cooling/contraction of the deposition medium for optimal results. The challenge is that these machines also have printing heads that move in 3 dimensions over a large space where covers for smaller printers do not scale up to this size.
Dynatect has provided machine roof covers for large 3D CNC milling machines for a decade. Traditionally these machine roof covers keep process generated debris contained in the enclosure, but for 3D printers they keep debris out with the added benefit of enclosing the space for easier air temperature management. The machine roof covers are well suited for large format 3D printers with optimized retracted/expanded ratio for full motion, rollers to accommodate high speeds, and translucent material so light still enters the work area.
For in-field robotic home printing, these are disruptive technologies that claim to offset more than 50% of the manual labor of conventional home construction. As a result, the variety and diversity of large-format 3D printing machines has significantly increased. Scalable industry growth is tied closely to repeatable performance and system durability. There are already proven solutions in adjacent industries like construction, machine tooling, and robotics that can be applied to this evolving field to maximize repeatability and durability. Those solutions will need some adaptation to be re-applied, and application-specific custom engineering is key success in new implementations.