Top ten tips for choosing a cobot

There are several reasons why cobots are gaining in popularity, as Paul Richards, Global Customer Coordinator Europe, Cobot Market, FANUC Europe, explains and offers tips on what to consider when choosing the right one for your process.

Paul Richards, Global Customer Coordinator Europe, Cobot Market, FANUC Europe

When the International Federation of Robots (IFR) first started collating collaborative robot data in 2017, this new breed of robot had a market share of just 2.8%. The IFR’s latest report showed that by 2021, that figure had leapt to 7.5%, with the number of newly deployed collaborative robots growing by 50% year-on-year to 38,966 units globally.

Firstly, they provide a solution to many of the challenges that manufacturers are facing in this ‘new normal’ era. In terms of flexibility, the cobot sits midway between an industrial robot and a human. This level of agility is valuable for accommodating the shorter product lifecycles and vast numbers of SKUs that are typical of the increasingly common HMLV (high-mix-low-volume) approach to manufacturing. Cobots can also help manufacturers counteract the ongoing issue of unskilled labour shortages by freeing up human workers to carry out more valuable tasks.

As demand for cobots has soared, the number of players in the market has proliferated and there are now over 60 cobot manufacturers worldwide. Whilst more competition can mean greater choice and better value for customers, it can also mean more confusion. This is particularly salient when you consider that cobot sales in the UK are being driven by SMEs, who seldom have the in-house resources and expertise to thoroughly assess numerous different makes and models. To aid the decision-making process, FANUC has compiled a checklist for companies to work through when purchasing a cobot, helping first-time buyers to navigate the complexities and avoid costly pitfalls…

1. Establish the business case
To determine whether your operation would benefit from a cobot, start by identifying the pain points that are hindering growth or performance. If staff reliability, RSI, health & safety concerns, a lack of labour, or the limitations of hard automation feature on your list, then cobots are a route worth exploring.

2.Identify potential applications
The next step is to identify the applications associated with these pain points. What are the tasks that are causing RSI? Which health & safety hazards could be removed such as lifting/moving heavy loads? Which are the tasks humans don’t want to do?

3. Evaluate the applications
Score each application based on the following considerations: Is it a precision task? Are there uncomfortable motions involved? Does it result in high rejection rates? Does it involve heavy loads? Is a constant human presence needed? Does the human operator add any value? What speed does the task need to be performed at? From experience we know that welding, pick & place and machine loading are often ideal candidates for cobot applications.

4. Cover off safety concerns
Assess the safety of your chosen application: does the cobot need to be guarded, unguarded or part guarded? FANUC cobots, depending on the application and risk assessment, can work safely alongside humans unguarded at speeds of up to 250mm per second, so speed is a good indicator as to whether a cobot is the right automation solution for the task. That said, it is not always clear cut. Part guarding or other safety devices can be employed to enable cobots to work alongside humans at higher speeds. However, if the application requires full guarding, making it less flexible and adding to the cost, a cobot may not be the right solution.

5. Protect your investment
The IFR considers the average lifespan of a robot to be 12 years; studies suggest this is a conservative estimate. To protect your investment, it is vital that you buy from a brand that is still going to be around in 13, 14, 15 or more years’ time and will support your cobot throughout its lifespan. Ask potential suppliers for the predicted life of their cobot, how long it will be supported for, how future proof it is in terms of software, and what warranty they offer. For example, FANUC’s CRX collaborative robot series comes with an eight-year zero maintenance guarantee.

6. Calculate payload and reach
The biggest mistake companies make with regard to payload is to go too low. Don’t assume that if a cobot has a payload of 5kg it can lift an item weighing 5kg. To work out your payload requirement, calculate the total load on the end of the arm (part + gripper + fingers etc) whilst taking into account offset payload and inertia. When calculating reach, bear in mind that working at full reach limits the cobot’s movement in the robot wrist, so build in additional margin. To help manufacturers choose the right payload and reach for their need, our CRX range comes in five sizes, from 5kg payload and 994mm reach up to 25kg payload and 1,889mm reach.

7. Select sensors and ancillary equipment
If your application requires 2D or 3D vision, consider where you want to mount the camera (remotely or on the cobot). If the cobot will always pick from the same area, a remote mounted camera is best mounted over the pick area, whereas a cobot-mounted camera will give you more flexibility. Force sensors (which give the cobot ‘feel’ functionality) can be internal or external. The use of vision will not only offer more flexibility but reduce the cost of fixturing required to position parts.

8. Evaluate your environment
If you are planning on using the cobot in a food production environment, you will need to think about IP rating and washdown protection. If the cobot is intended for use in a dusty or dirty environment or is likely to come into contact with machine coolant, you will also need a high protection rating (IP67 or above). When enquiring about IP ratings, make sure that they apply to the entire unit (including the controls), not just the arm. Every model in FANUC’s CRX range is IP67 rated and the food version is covered in a white epoxy coating with food-grade grease, making it safe for use in food production facilities.

9. Consider connectivity
Does the cobot need to communicate with other equipment, such as CNC machines, part feeding systems, grippers or vision systems? If so, specifying your cobot with the same communication protocol as peripheral equipment will save cost and integration time. If possible, keep it simple by using standard I/O. However, some applications require Fieldbus as it enables larger amounts of data to be communicated to peripheral equipment.

10. Plan for the future
Finally, think about how flexible the cobot is for meeting your future needs. Will it be able to accommodate new applications and growth? Does it have software that can be updated and supported? Also bear in mind that if you buy from a company that solely manufactures cobots and in future you need an industrial robot, there will be a new learning curve.

There is a lot at stake when purchasing a cobot for the first time. As well as driving productivity and health & safety performance improvements, a positive experience will pave the way for further automation of more profitable applications and inspire employees as you continue on your automation journey.

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