- Metal belts are strong. Multi-layered metal belts are stronger.
- Metal resists scratches and bruises, giving bacteria space to hide and breed.
- Metal belts will not create dust or debris.
Single-stage metal belts are stronger than plastics or rubber belts. But they may still lack the strength and endurance in handling applications that involve heavy lifting and repetitive movements, such as robots. In these cases, multi-layer metal belts are a better option.
But are multi-layered metal belts a good choice for your design or application?
Here is a look at the advantages and disadvantages of multilayer metal belts compared to their single-row and non-metallic belts.
Metal Belt Basics
Multi-row belts are similar to single-row belts in design, and can be used in both endless or open-ended configurations.
An endless metal belt is one continuous sheet of metal welded together in a loop. Such a belt is durable and provides consistent, resilient performance, making it useful in automated assembly, food processing and medical devices.
Metal drive tapes, on the other hand, are fixed in an open arrangement. They share metal construction with belts but are anchored at each end. They are commonly used for highly accurate movement and repetition, which is essential in the manufacture of 3D printers and robots.
Metal belts can be made from a combination of stainless steel and titanium alloys, as well as nickel alloys such as Inconel and Invar. Some of these materials resist low temperatures, others resist corrosion, and some have high tensile strength and yield. The choice of material depends on the intended application.
Just like their single-layer counterparts, multi-layer drive tapes offer zero backing, which occurs as a result of excessive clearance between the time zone holes and the time-lapse pin. A little cleaning is usually needed to prevent it and allow the pins to go into holes, but it can cause backing when the belt is turned back on.
When the pulley turns to move the belt back the pins must move from one side of their holes to the other before pressing the belt. This small backlash can introduce positional errors into the movement profile. Precise metal belts can be designed to eliminate this.
Multi-layered belts consisting of 2-7 bands are stacked with a thickness from 0.003 to 0.005 in.. This reduces the overall weight applied to the belt and allows the belt to carry greater tensile loads over its cross-sectional area. The added strength also extends the working life of the belts.
The layered construction also adds stiffness, which increases its elasticity model so that the belt can withstand backing due to any gaps left between the timing holes and the inexhaustible pins. out. This can be helpful in many applications. For example, some robotic arms have two steel belts working together with one belt driving the foot movement. Thanks to the instability of the steel belt, this design can quickly accelerate and reverse without causing backlash. Multi-row belts are usually used in this way to handle high loads and accelerations.
Multi-row belts are more difficult to make because of all the layers that need to be meticulously made and then welded together at the end tab of the belt. Each belt cover has a slightly different length and needs to be tied so that it can match the other layers when wrapped around the ula. The rear tab is another key element in ensuring a long belt life as it is exposed to high levels of pressure. Because of this, the design of the tab is as important as the high-quality, precise welding used to create it.
Multi-layered belts offer many benefits, including their strength and flexibility, but they have several others.
Belt thickness and pulley size determine the longevity of the belt. A larger pulley usually means that a belt can carry larger loads. But multi-layered belts can carry high loads without increasing the diameter of the shaft. The multiple layers provide thicker band strength but work together to have less band flexibility. Applications that take full advantage of multi-layered metal belts include moving heavy loads without space for the right-sized crane required for a single-layer but thicker belt. This design accommodates a pulley diameter as small as 1.5.
As mentioned before, it is more difficult to produce multi-layered metal belts, which leads to a higher initial cost. This is a disadvantage, but these belts are more cost-effective over their lifetime due to increased durability.
Compared to traditional non-food belts, the longer life of multi-layer metal belts and lower cleaning and maintenance requirements help correct the face cost and make them a better choice in the long run.
Metal belts can be deformed outside of repair when used improperly or under severe impact. Keeping metal belts, single- or multi-layered, safe from this type of damage is essential to ensure a long-lasting belt.
Multi-Layer Metal Belts in action
A company was trying to test and commercialize new technologies for robotic applications. The projects included new ways to lift and turn heavy loads in the areas of conservation, logistics, medical and food processing.
The company was working on one machine that used a single-layer metal belt made of local metal. The belt measured 6 mm wide by 0.2 mm dry, but failed when the torque on a belt exceeded 25 Nm. The client then worked with an engineering team from Belt Technologies.
One of the challenges was that they could not change the diameter of the floor. So the team designed and made a stainless steel belt with six layers, each 0.125 mm dry. It allowed the machine to handle the required 150 Nm of torque without increasing the bending pressure. As a result, total weights on the belt decreased, increasing its life.
The company saw the success of the belt protocol, which was used mainly for displays, and ordered versions of the new metal belts with slightly modified lengths for use in healthcare devices.
Speaking of health care claims, metal belts allow medical device manufacturers to meet safety regulations for motorized conveyor belts in pharmaceutical and medical applications. Metal belts, unlike plastic or rubber versions, are resistant to bacteria that can contaminate medicines. They are also healthier as they are easier to clean and water / detergent protected.
Multi-layered metal belts find space in robots. Open-cast metal drive tapes, a type of multi-fold belt, can perform multiple functions with a near-zero backlash, including:
- Location carbadan
- Moving robotic arms
- Manufacturing LCDs
- Optical element drivers
Are they right for you?
In addition to superior strength and flexibility than single-row belts, multilayer belts have the features and advantages of multilayer belts, including:
- High strength-to-weight ratios
- Durability and longer belt life than other options
- Rigid (non-stretching) for more precision
- Resist variable temperature
- Resist corrosion, rust and overheating
In addition, they are:
- Do not require lubrication
- Adheres to the strictest USDA requirements for food production
- Allow high accuracy and repeatability
- Is nonporous and resists surface damage
- They are very suitable for different industries and applications
- Do not generate items such as HTD or flat neoprene belts, making them well suited for clean room applications.
Denis Gagnon is CEO and Alan Wosky is president of Belt Technologies Inc. in Agawam, Mass. Contact them here.