Parts Feeding for Cobots: Reaching into a Bin, Trays, or Flexible Feeding?
The cobot has been purchased, and the first program is up and running in no time. And then comes the question that no data sheet answers: How do the parts get to the robot so that it can grasp them reliably? Companies that commission their cobot without an integrator, in particular, realize at this point that the grasping process is rarely the problem. The problem lies before that.
This guide compares the three common methods of part feeding for cobots, highlighting their strengths and limitations. It also candidly explains when a flexible feeder like feedy isn't the right choice.
Why Deployment Is a Decisive Factor in the Cobot Cell
A cobot can only pick up what it finds. It needs the part to be in a known position and orientation. If the parts are loose in a box, neither of these conditions is met. Three questions can help clarify the situation:
- How are the parts delivered today: as bulk material, arranged in a tray, or directly from an upstream process?
- How many different parts is the cell expected to process in the coming years?
- What is the cell's actual cycle time?
Once you've answered these three questions, you're usually halfway to making a decision.
Option 1: Reach into the box with a 3D camera
When retrieving items from the bin (known in technical jargon as “bin picking”), a 3D camera is positioned above the container. Software calculates a grasping point for each part, and the robot picks it up directly from the bulk material.
Advantages: The parts do not need to be pre-sorted and remain in the container in which they are delivered. This works well for larger, sturdy parts with clearly defined gripping surfaces.
Limitations: With small parts that overlap or get caught on each other, reliability decreases noticeably. Camera calibration, gripper planning, and collision avoidance with the container wall require experience; without an integrator, this is a challenging project. Often, after the initial grasp, an additional set-down is needed to reposition the part because it was not grasped in the orientation required for assembly. Added to this is throughput: it is usually limited to a maximum of about 10 parts per minute.
This works if the parts are larger, arrive in boxes from the supplier, and the orientation doesn't matter much after they've been handled.
Method 2: Trays and Workpiece Holders
The parts are neatly arranged in compartments. The cobot follows a fixed pattern and does not require image processing.
Strengths: The easiest to program and very reliable. Delicate or valuable parts remain protected.
Limitations: Someone has to fill the trays. If this is done by hand, the manual labor is simply shifted to another location. Each part requires its own tray; new variants mean new trays and additional storage space. And how long the cell can run without an operator depends on how many trays are available.
This works well when the parts are already sorted by the supplier or from the previous process, and only a few variants are being produced.
Method 3: Flexible Feeding with a Camera
In flexible feeding—often called a “flex feeder”—bulk material is fed in and separated; a camera detects the orientation of each part. feedy then positions the parts in the correct orientation at a fixed transfer position. This means the cobot always picks up the parts from the same spot. When a new part arrives, it is programmed rather than requiring a setup change; a product changeover takes about one minute.
Strengths: Bulk material remains bulk material; no one has to fill trays. Many different variants can run through the same system. The cobot program remains simple because the transfer position is fixed. feedy does not require a safety enclosure and thus fits in with the cell’s collaborative concept; at 120 × 40 × 50 cm, it also fits into existing workstations.
Limitations: The range of parts is limited. feedy processes parts ranging from 3 to 50 mm in size and weighing up to 30 g, provided they are dry, clean, and non-magnetized. The system can process up to 40 parts per minute. The investment cost is higher than that of a set of trays and pays off especially in applications where part variants change frequently.
This is suitable when small parts arrive in bulk, when there are frequent changes, or when many variants are processed on a single cell.
And what about the classic spiral conveyor? For a single part in mass production, it's hard to beat. Our comparison shows where it reaches its limits.
A Comparison of the Three Approaches
| Criterion | Reaching into the box | Trays | Flexible Feeder (feedy) |
|---|---|---|---|
| Parts come as | Bulk goods | arranged in the tray | Bulk goods |
| Preparatory work by staff | none | Filling and Replacing Trays | Refilling Bulk Material |
| Performance | usually no more than about 10 parts per minute | Depending on the cobot; pause during tray change | up to 40 parts per minute |
| New Item | Adjust and Test Gripper Planning | new tray | train, about one minute |
| Part Size | larger pieces with clearly defined gripping surfaces | virtually any | 3 to 50 mm, up to 30 g |
| Programming Effort for the Cobot | high (camera, grasping planning) | low (grid) | low (fixed handoff position) |
| Position after the grip | Often requires repositioning | defined | defined |
| Typical Applications | Larger parts; orientation not critical | few variants, delicate parts | Small parts, many variations |
When a Flexfeeder Isn't the Right Choice
A flexible feed system is not a panacea. In these cases, we recommend a different solution:
- Very high throughput: If the cell requires more than 40 parts per minute, a conventional conveyor is the better choice. In many cobot cells, however, the cycle time is a few seconds per part; in such cases, the feed is rarely the bottleneck.
- Large or heavy parts: Anything larger than 50 mm or heavier than 30 g belongs in a different solution—for example, the handle in the box.
- Oily, wet, or magnetized parts: They cannot be reliably separated.
- Parts arrive already organized: It would be a waste to turn them into bulk goods first. The tray is the simpler solution here.
- Single part, high volume, no changeovers: This is where the spiral conveyor really shines.
If any of these points apply, we'll let you know openly in the parts evaluation.
What Businesses Without an Integrator Should Keep in Mind
The risk assessment remains. A cobot does not automatically make an application safe. The entire application is assessed: the gripper, the part, the motion, and the environment. A feed system without a guarding enclosure makes this easier, but it does not replace the assessment.
Keep the handoff simple. A fixed grip point reduces programming and calibration effort. The less the cobot has to search on its own, the more stable the cell operates.
Consider the gripper. Suction cup or jaw gripper? If different parts are to pass through the cell, changing the gripper must be factored into the planning.
Test with actual parts. Flash, tolerances, and surface finishes from actual production behave differently than those of sample parts. A test using your own parts reveals more than any data sheet ever could.
Plan for refilling. How long should the cell run without an operator? This determines how large the supply at the feed point needs to be.
Frequently Asked Questions
What is the easiest way to supply parts to a cobot?
For parts that arrive already sorted, trays are the simplest option. For small parts in bulk, a flexible feeder with a fixed transfer position is usually the easier solution because the cobot doesn't need its own camera.
Does my cobot need its own camera when it's working with feedy?
No. The camera is integrated into feedy. feedy identifies the parts and positions them correctly at a fixed location; the cobot picks them up from there.
Is feedy compatible with my cobot?
feedy works with common cobot and robot systems. We'll determine which integration is right for your cell during the part evaluation.
How fast is feedy?
Up to 40 parts per minute—that is, about one part every one and a half seconds.
Does feedy need a protective enclosure?
No, feedy can be operated without a protective enclosure. However, a risk assessment is still required for the entire cobot application.
Can I try out feedy before I invest?
Yes. The parts evaluation takes no more than one week and is free of charge. After that, you can test feedy in your facility for 3 months. At the end of that period, you decide: purchase it at the quoted price or return it for a flat fee of €5,000.
Your Parts, Your Cobot, Your Test
Send us your components for evaluation; there is no charge. You will receive the results along with a video of the test using your own components.