Leslie Langnau, Managing Editor
With belt driven linear actuators versus re-circulating ball bearing systems, the fact is both have a place in an automation design. Belt-drive systems suit shuttle transport and conveyance applications well, especially if you are trying to achieve high speeds over long stroke lengths. They often fare better than lead screws for high speed/long stroke applications, especially in vertical applications where lead screw-driven systems may be prone to noise and resonance.
The belts are designed to maintain the proper tension over the actuator’s lifetime (providing they are used within the guidelines of the published specifications), so there is no need to be concerned about belt elongation. Industries using belt-driven systems include laboratory automation, packaging machinery, gaming and amusement equipment, screen-printing, test fixtures, and many other applications where quiet operation and dry-running systems are critical.
DryLin® ZLW tooth-belt driven linear actuators were designed as low-cost, shorter lead time alternatives to traditional re-circulating ball bearing systems which sometimes cost thousands of dollars. They are engineered with wear-resistant, dry-running, oil-free linear bearings which do not require maintenance.
These systems suit applications requiring quick positioning of small to medium loads at high speeds (up to 5 m/s), at stroke lengths up to 3000 mm. The larger DryLin ZLW-1660 profile has higher radial load capabilities (2000 N) 450 lb for applications requiring a more robust system. Since the parts operate as sliding systems as opposed to rolling systems, high accelerations are possible without galling or damaging the guide rails, which may help increase machine throughput.
The linear positioning tolerance of belt-driven systems is generally greater than that of lead screw driven systems. Some belt drive systems that operate on linear plain-bearing technology do not differ that much from higher cost systems relying on re-circulating ball bearing technology. Depending on the system, expect tolerance to range from ± 0.2 mm to ± 0.35 mm.
Here is a quick checklist to see if DryLin® ZLW systems will suit your application:
- Loads from 0 to 150 N (33 lbF) for the most common size range. 2000 N (450 lbF) for larger, heavy duty systems.
- Max speeds lower than 5 m/s (16.4 fps).
- Stroke lengths 1 mm – 3000 mm. Longer strokes may be possible.
- Minimum linear positioning ± 0.2 mm.
- Belt-drive systems suit applications with high duty cycles as there is no concern about frictional heat buildup in the nut.
- For low-weight vertical actuator applications.
- For applications in sensitive environments such as laboratory or food processing equipment.
The DryLin ZLW systems are based on hard-anodized aluminum guide rail profiles, which offer a good mating surface for the linear bearing liners. Several linear bearing housings are available including low-cost zinc-castings, lightweight and corrosion-resistant hard-anodized aluminum machined parts, as well as adjustable versions which allow the flexibility to eliminate or increase the linear bearing clearance per the application requirements.
Filed Under: TECHNOLOGIES + PRODUCTS, Actuators, ALL INDUSTRIES, Design World articles, Linear motion • slides, Motion control • motor controls