Start with the question, not the equipment
A conveyor that suits one plant can be a poor choice in another, even for similar products. Selection works best as a sequence of questions about what has to be moved, how far, how fast and in what conditions. Only after those are answered does it make sense to compare designs. The families themselves, such as belts, rollers and chains, are described under conveyor types. This article is about the decision process.
1. What is being moved?
Describe the load as precisely as possible.
- Form. Individual items such as cartons, totes, pallets or parts, or loose bulk material like grain, aggregate or powder.
- Size and weight. Both the heaviest item and the typical one, including the weight per unit of length for a full conveyor.
- Shape and base. A firm, flat base behaves very differently from a soft bag, a round object or something with protrusions.
- Condition. Hot, wet, oily, sticky, abrasive, sharp, fragile or sensitive to marking.
- Variation. The full range of products it must handle now and in the foreseeable future.
If the range of items is wide, design for the awkward cases, not only the average.
2. Where does it go?
Distance, height change and path shape matter.
- Length and the number of turns.
- Inclines or declines, and how steep. Some surfaces handle slopes better than others.
- Obstacles, doorways, columns and crossings with walkways or forklift routes.
- Whether items must be lifted vertically, which may call for an elevator or other lifting device, such as bucket elevators for bulk.
Long runs raise power needs and the importance of alignment and tracking. Tight spaces may call for compact designs or vertical solutions.
3. How much, how fast?
Capacity is not the same as belt speed. Figure out the number of items or the amount of material per hour needed at peak, not only on average. Then consider spacing between items, because the rate equals item count per length times speed. Allow some margin, but not so much that the system is oversized and costly. How speed is matched along a line, and how throughput is increased, is discussed in conveyor throughput.
Also think about stops and starts. Frequent starts put more stress on motors and drives than steady running does, and heavier loads need more careful drive selection.
4. What conditions will it work in?
The environment can rule out a design.
- Temperature. Very hot or cold areas affect belt materials, lubricants and electronics.
- Moisture and washdown. Food, beverage and pharmaceutical plants usually need materials and designs that can be cleaned thoroughly.
- Dust and combustible materials. Some atmospheres require specially rated equipment and strict control of ignition sources. This is a matter for qualified specialists and local regulations.
- Corrosive chemicals or outdoor weather. These influence materials and coatings.
- Noise limits. Some designs are quieter than others.
5. How will it be controlled?
Decide how items are detected, spaced and routed. Simple setups may use one motor and a start button. Complex ones use sensors, zones, diverters and programmable logic controllers working together, perhaps linked to scanners or sorting software. Think about how the conveyor will connect to adjacent machines, whether packers, palletizers, or robots, because mismatched handover points are a common cause of problems.
6. What about safety?
Conveyors involve pinch points, rotating parts, and the risk of entanglement. Likely requirements include guards, emergency stop devices, safe access for cleaning and clearing jams, warning signs and lockout tagout provisions for servicing. Include these in the specification from the start. They are easier to design in than to add later. Requirements vary by region, so check local regulations and the manufacturer’s documentation.
7. Who will maintain it?
A design that matches the load but cannot be maintained by the available staff is a poor choice. Consider:
- Accessibility of parts that wear, such as belts, rollers, chains and bearings.
- Availability of spare parts and lead times.
- Training needs.
- What routine conveyor maintenance will involve.
Think about downtime too. If the conveyor feeds a critical process, think about what happens if it stops.
8. What does it really cost?
Compare options on total cost of ownership: purchase, installation, electrical work, guarding, energy, maintenance, spare parts and expected life. A cheaper unit that wears quickly or jams often can cost more over time. New versus used, and buying versus leasing, are further considerations that are covered under pre-owned equipment benefits and equipment leasing.
9. Will needs change?
Products and volumes change. Modular designs, extra capacity in the drive, and space for extension make growth easier. But paying for large future capacity that may never be used is also wasteful, so judge the likelihood sensibly.
Quick reference checklist
Before approaching suppliers, write down:
- Item or material description, sizes, weights, and condition.
- Required rate at peak.
- Path, length, heights, and obstacles.
- Environment and cleaning needs.
- Control and connection requirements.
- Safety and regulatory requirements.
- Maintenance resources.
- Budget and expected life.
- Expected growth.
Working with suppliers
Share this information, ask them to explain why they recommend a particular design, and ask for references with similar loads. Visiting a working installation can reveal practical details that brochures miss. Where possible, test with real product samples. This article is general information and not engineering advice, and qualified engineers should confirm the final specification.