The essential guide to robot screw feeding: How screw feeders work and why you need one

August 17, 2023
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What is a screw feeder and why does my robot need one?

Screw feeders, also known as bolt feeders or fastener feeders, are automated devices that orient and feed screws and bolts for pickup by the robot end-effector. A screw feeder is one of the most important attachments for your Industrial robot. Without it, your robot wouldn’t be able to pick up and place screws, bolts or other fasteners. 

Screw feeders typically have a hopper to hold a large number of screws, a sorting mechanism to properly orient the screws, and a feeding mechanism to bring the screws within the robot’s reach. The basic steps are:

  1. The screws are loaded into the hopper.
  2. The screws travel down a tube or channel where they are mechanically oriented into the correct position.
  3. Once oriented, the screws are fed one by one to a location where the robot end-effector can grasp them or load them.
  4. The robot then places or fastens the screw where it is needed.

For the system to work properly, you need the right screw feeder for your particular screw size and shape. You also need an end-effector specifically designed to grasp that type of screw. End-effectors, also known as end-of-arm tooling, are attachments at the end of the robot arm that can grasp and manipulate objects.

Major Industrial robot manufacturers like FANUC, ABB, KUKA, and Standard Bots offer screw feeding systems and end-effectors to suit their robot models. When selecting a screw-feeding system, consider the robot model, screw size and shape, feed rate, and orientation required. 

How industrial screw feeders work

A screw feeder is an important component of an Industrial robot. It's what delivers screws — or bolts — to the robot so it can drive them into parts during assembly. Without a reliable screw feeder, your robot wouldn't have anything to fasten parts together.

Screw feeders come in a variety of types, like bowl, rail, and hopper feeders. Bowl feeders use a vibrating bowl to move screws to an exit chute where the robot can pick them up. Rail feeders slide screws down a channel to the robot. And hopper feeders drop screws from a container onto a conveyor that moves them to the robot.

For the feeder to work with your robot, the screw delivery point needs to be in the right position so the end-effector can access the screws. The feeder also needs to supply screws at the correct rate to match your required assembly speed. If screws jam or run out, it interrupts production, so maintenance and monitoring are key.

Understanding how they operate and the options available will help you choose a feeder optimized for your robot, screw, and production needs.

Choosing the right screw feeder for your robot

Choosing the right screw feeder for your robot is crucial to ensure fast, accurate performance. For the best results, consider the following factors:

Screw size and shape: The feeder bowl must be designed to properly orientate your specific screw. Round, flathead screws are the easiest, while screws with irregular shapes may require a custom bowl.

Feed rate: How quickly does your robot need to pick up screws? Faster robots will require a higher feed rate to keep up. Look for a feeder bowl that can supply at least 20-30 screws per minute for most medium-speed robots. The exact appropriate number will depend heavily on how many screws your robot needs to place per part, and how long each cycle takes — in other words, how long it takes your robot to move across each part and insert all of the required fasteners.

Bowl capacity: For high-volume production, choose a larger bowl that can hold more screws, so the robot won’t have to pause while it’s refilled as often. Bowls are available in sizes from 1 liter up to 20 liters or more. In an ideal scenario, your robot will be able to operate for hours or days without intervention from your team. While larger bowls are more expensive, the reduction in downtime normally makes this an ROI-positive investment.

End-effector compatibility: The end-effector, or “hand” on the end of the robot arm, must be designed to properly grasp the oriented screws from the feeder bowl outlet. If the robot will not be loading fasteners directly into e.g. a nail gun or screw-driving end-effector, then vacuum grippers, magnetic pickups, and mechanical grips are common options. Ensure the end-effector and screw feeder supplier work together for the best solution.

Your robot will have a fast, reliable system for picking and placing screws in your assembly application when you use a properly-matched screw feeder and end-effector. With some fine-tuning, you'll achieve optimal productivity and throughput.

The importance of end-effectors and tooling

End-effectors are one of the most important parts of any robot system. They are the “hands” attached to the end of the robot arm that physically interact with parts, tools, and the environment. For a screw-feeding application, the end-effector is the device that holds and positions the screw to be fed into a part or subassembly.

There are many types of end-effectors for Industrial robots, including:

  • Gripper - Grabs and holds parts. Can be single or multi-fingered.
  • Screw-driving - Uses an attached tool to drive fasteners into a part.
  • Clamp - Has two opposing jaws to grasp parts.
  • Screw feeder - Feeds, carries, and places screws and fasteners for another robot or end-effector to utilize.

End-effectors are designed specifically for presenting screws in the proper orientation to a part. Some key factors to consider for your screw-feeding end-effector include:

  • Screw size capacity - Make sure the feeder can handle the screws you need to feed.
  • Screw orientation - It must be able to pick up screws and orient them properly for the application.
  • Interface - Ensure the end-effector has the right mounting interface for your robot. This way, you can ensure optimal performance, safety, and ease of use while avoiding potential issues related to mismatched interfaces.
  • Reliability - Search for end-effectors that are specifically engineered for high-speed, high-volume assembly tasks that possess a favorable rating. This will enable you to maximize the operational lifespan of your screw feeder, ensuring optimal performance over extended periods.
  • Ease of loading - To achieve peak productivity, your ideal end-effector should offer swift and effortless screw reloading, eliminating the need for any human intervention. 

By choosing an end-effector designed specifically for your screw feeding needs and optimizing it to work seamlessly with your robot, you’ll ensure maximum efficiency, productivity, and uptime in your automated assembly process. The end-effector is the critical link between the robot and its task, so it’s worth investing in a high-quality, application-specific solution.

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Major manufacturers of robots

FANUC

FANUC stands as a prominent Japanese robotics corporation renowned for manufacturing a variety of robots, notably the ARC Mate 100iC and LR Mate 200iD. Employing cutting-edge technology, FANUC incorporates force control sensors and advanced 3D vision systems to skillfully guide the robots throughout their operations. 

KUKA

KUKA, a distinguished German robotics enterprise, also stands as a significant player in the field. KUKA provides Articulated robots equipped with force sensors and vision guidance, ensuring precise operations. Additionally, KUKA produces linear robots that glide along tracks, perfectly suited for sanding vast and flat surfaces.

ABB

ABB, a prominent Swiss robotics corporation, takes the lead in offering a wide range of robotics solutions for industrial processes. Their IRB series encompasses both Articulated robots and linear models tailored for this purpose. With the aid of ABB’s RobotStudio software, users can easily program and visualize entire processes. The versatility of ABB’s robots is evident as they efficiently handle various materials, including wood, metal, plastic, and glass.

Standard Bots

Standard Bots, a robotics manufacturer based in the United States, boasts an impressive position in the industry. Their RO1 Six-Axis robot is highly versatile and fits seamlessly into various applications. The company’s distinguishing features include competitive pricing, cutting-edge, no-code programming capabilities, and exceptional precision, making them an excellent choice for robotic processes.

Next steps

So there you have it, everything you need to know about robot screw feeders to make an informed purchasing decision. These handy devices can save you time, money, and hassle in your factory. 

Now you understand how they load screws, why they’re critical for high-volume assembly, and what to consider when choosing one for your robot. With the right screw feeder and end-effector, your robot will work faster and more accurately than ever before. 

Interested in bringing an Industrial robot to your own business? RO1 by Standard Bots is a great choice for machine shops large and small:

  1. Affordable: RO1 is the most affordable robotic arm in its class, starting at almost half the price of incumbent competitors. 
  2. Powerful: RO1 is faster and more precise than competitors, despite having the highest payload capacity in its class at 18 kg.
  3. Integrated: RO1 comes equipped with built-in relays to control almost any machine on the market, including plug-and-play support for Haas CNC milling machines.

Speak to our solutions team today to organize a free, 30-day onsite trial and get expert advice on everything you need to deploy your first robot.

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