Title: Chapter 24: Cycle Time |
Short Summary |
Cycle time is one of the most practical performance metrics in industrial robotics. It measures how long a robot takes to complete one full work cycle, from picking up a part to placing it and returning to the start position. In many industries, cycle time directly determines throughput, cost per unit, and competitiveness. Delta robots achieve the fastest cycle times measured in tenths of a second, followed by SCARA robots, while Cartesian and articulated robots are slower but carry higher payloads. This chapter explores how cycle time shapes real applications across dozens of industries, from food packaging and electronics to automotive assembly and pharmaceuticals. It explains why a fast robot is not always the best robot, and why the right choice depends on the balance between speed, payload, precision, reach, and cost. The chapter uses plain language and real-world examples, avoiding formulas and tables, to help readers understand how cycle time influences robot selection and system design. |
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1. Understanding Cycle Time in Industrial Robotics |
Cycle time is the time required for a robot to complete one full sequence of movements and return to its starting position. In a pick-and-place application, that sequence might be: move to pick position, close gripper, lift part, move to place position, open gripper, and return to pick position. In a welding application, it might be: move to weld start, follow weld path, retract, and move to next weld start. In a machine tending application, it might be: reach into machine, grab finished part, pull out, place part, and load new blank. |
Cycle time is usually measured in seconds, tenths of a second, or even milliseconds. For high-speed Delta robots, cycle times of 0.2 to 0.5 seconds are common. For SCARA robots, cycle times of 0.5 to 1.5 seconds are typical. For Cartesian and articulated robots, cycle times often range from 1 to 5 seconds or more, depending on payload and distance. These numbers are not absolute limits. They depend on the distance traveled, the payload, the acceleration and deceleration profiles, the gripper speed, and the control software. |
The importance of cycle time varies by industry. In food packaging, a difference of 0.1 seconds per cycle can mean thousands of extra packages per shift. In automotive assembly, a difference of a few seconds per cycle can affect the entire production line balance. In pharmaceutical filling, cycle time must be fast enough to meet production targets but also consistent enough to meet regulatory requirements. In electronics, cycle time affects the cost of assembling millions of devices. In logistics, cycle time determines how many orders can be picked and packed per hour. |
However, cycle time is not the only metric that matters. Payload, repeatability, reach, and reliability are also critical. A Delta robot may be incredibly fast, but it can only carry a few kilograms. A large articulated robot may be slower, but it can carry hundreds of kilograms. A SCARA robot offers a good balance of speed and payload for many assembly tasks. A Cartesian robot can be very precise and can cover large rectangular work areas, but it may be slower than a Delta or SCARA robot. The best robot for a given application is the one that meets the required cycle time while also meeting payload, precision, and cost requirements. |
This chapter focuses on cycle time as a performance metric. It explains how different robot types compare, and then it explores dozens of real-world applications across many industries. Each section describes how cycle time affects the application, what robot types are commonly used, and what trade-offs are involved. The goal is to help readers understand that cycle time is not just a number. It is a key design parameter that shapes the entire robotic workcell. |
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2. The Speed Hierarchy: Delta, SCARA, Cartesian, and Articulated |
The speed hierarchy of industrial robots is well established. Delta robots are the fastest. They use a parallel kinematic structure with three or four lightweight arms connected to a common base. This design reduces moving mass and allows very high acceleration. Delta robots are often used for pick-and-place tasks where the payload is light, typically less than 5 kilograms. Their cycle times can be as low as 0.2 seconds for short moves. They are common in food packaging, electronics assembly, and pharmaceutical sorting. |
SCARA robots are the next fastest. SCARA stands for Selective Compliance Assembly Robot Arm. They have two parallel rotary joints for horizontal movement and a linear joint for vertical movement. This design makes them very fast in the horizontal plane and very stiff in the vertical plane. They are ideal for assembly tasks that require fast horizontal moves and precise vertical insertion. Payloads typically range from 1 to 20 kilograms. Cycle times are often 0.5 to 1.5 seconds. |
Cartesian robots, also called gantry robots, use linear axes to move in X, Y, and Z directions. They can be very fast over long distances, but they have more moving mass than Delta robots. They are often used for large work areas, such as pick-and-place over conveyor belts, machine tending, and 3D printing. Payloads can range from a few kilograms to hundreds of kilograms. Cycle times depend on the size of the work area and the speed of the linear axes. For small areas, cycle times can be around 1 second. For large areas, cycle times can be several seconds. |
Articulated robots have a serial kinematic structure with multiple rotary joints, similar to a human arm. They are the most versatile robot type. They can reach around obstacles, work in complex 3D spaces, and carry heavy payloads. However, their serial structure means they have more moving mass and lower stiffness than Delta or SCARA robots. As a result, they are generally slower. Cycle times for articulated robots often range from 1 to 5 seconds for typical pick-and-place tasks, and longer for complex paths. Payloads can range from a few kilograms to over 1,000 kilograms. |
The hierarchy is not absolute. A well-designed Cartesian robot can be faster than a poorly designed SCARA robot. A large articulated robot can be faster than a small Delta robot if the Delta robot is carrying a heavy payload or moving a long distance. But in general, the hierarchy holds: Delta robots are fastest, SCARA robots are second, Cartesian robots are third, and articulated robots are fourth. This hierarchy is important because it guides robot selection. If cycle time is the top priority and the payload is light, a Delta robot is usually the best choice. If cycle time is important but the payload is moderate, a SCARA robot is often better. If the work area is large or the payload is heavy, a Cartesian or articulated robot may be the only option. |
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3. Cycle Time in Food and Beverage Packaging |
Food and beverage packaging is one of the most demanding applications for cycle time. Products must be moved quickly, gently, and hygienically. Delta robots dominate this industry because they are fast, lightweight, and easy to wash down. They are often mounted above a conveyor belt and use a vision system to locate randomly oriented products. They then pick the products and place them into trays, boxes, or bags. |
Consider a high-speed snack food packaging line. A Delta robot might pick 200 small bags per minute and place them into a carton. That is a cycle time of 0.3 seconds per bag. If the robot were 0.1 seconds slower, the line would lose 40 bags per minute, or 2,400 bags per hour. Over a year, that lost throughput could cost millions of dollars. This is why food companies invest in the fastest Delta robots available. |
In beverage packaging, Delta robots are used to pick bottles, cans, and caps. They might place caps onto bottles at 300 cycles per minute. They might sort bottles into cases at 150 cycles per minute. They might pick defective bottles off a conveyor at 400 cycles per minute. In all these cases, cycle time is the key metric. The robot must keep up with the conveyor speed, which is often constant. If the robot is too slow, the conveyor must be slowed down, which reduces overall throughput. |
SCARA robots are also used in food packaging, especially for tasks that require more force or precision. For example, a SCARA robot might pick a jar and place it into a box, then tighten the lid. The cycle time might be 1 second. This is slower than a Delta robot, but the SCARA robot can handle heavier jars and can apply more torque. In some cases, a SCARA robot is used because it can be mounted on a wall or ceiling, saving floor space. |
Cartesian robots are used in food packaging for large work areas, such as palletizing. A Cartesian palletizer might pick a case of food and place it onto a pallet. The cycle time might be 3 to 5 seconds per case. This is slower than a Delta robot, but the Cartesian robot can carry heavy cases and can cover a large pallet area. Articulated robots are also used for palletizing, especially for heavy bags and drums. Their cycle times are similar to Cartesian robots, but they can reach around obstacles and can work in tighter spaces. |
In all these food and beverage applications, cycle time must be balanced with food safety. The robot must be easy to clean, and it must not contaminate the food. Delta robots are often made of stainless steel and use food-grade lubricants. They are designed with smooth surfaces and no crevices where bacteria can grow. SCARA robots may have sealed joints and washdown capabilities. Cartesian and articulated robots may be enclosed or covered to protect the food. Cycle time is important, but it never comes before food safety. |
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4. Cycle Time in Electronics and Semiconductor Manufacturing |
Electronics manufacturing is another industry where cycle time is critical. Products are small, lightweight, and produced in huge volumes. Delta robots and SCARA robots are widely used. Delta robots are used for picking and placing tiny components onto printed circuit boards. They can achieve cycle times of 0.2 to 0.4 seconds per component. This is essential because a single circuit board may have hundreds or thousands of components. If each component takes 0.1 seconds too long, the total assembly time increases by minutes, which reduces throughput. |
SCARA robots are used for more complex assembly tasks, such as inserting connectors, screws, and shields. They can achieve cycle times of 0.5 to 1.5 seconds. They are often used in surface mount technology lines, where they pick components from feeders and place them onto boards. They are also used in final assembly, where they assemble housings, displays, and batteries. |
In semiconductor manufacturing, cycle time is measured in milliseconds. Robots must move wafers from one process chamber to another with extreme precision and speed. Delta robots are sometimes used for wafer handling, but more often, specialized Cartesian robots or articulated robots are used. The cycle time for a wafer transfer might be 1 to 3 seconds. The robot must be fast, but it must also be clean. Any particle generated by the robot can ruin the wafer. Therefore, the robot must use vacuum-compatible materials and special bearings. Cycle time is important, but cleanliness and reliability are equally important. |
In electronics, cycle time also affects the cost of production. A factory that produces 10 million smartphones per year might have thousands of robots. If each robot is 0.1 seconds faster per cycle, the factory can produce more phones per year without adding shifts or equipment. This is why electronics companies are among the first to adopt new high-speed robots. They are also among the first to use advanced vision systems and AI-based motion planning to reduce cycle time. |
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5. Cycle Time in Automotive Assembly |
The automotive industry is the largest user of industrial robots. Articulated robots dominate because they can carry heavy payloads and can perform complex tasks such as welding, painting, and assembly. However, cycle time is still a critical metric. In automotive assembly, the production line is often balanced so that each station takes the same amount of time. If one station is slower than the others, it becomes a bottleneck. The entire line must slow down to match the slowest station. |
Consider a welding station. An articulated robot might perform 20 welds on a car body. Each weld takes about 2 seconds, including movement, positioning, and welding. The total cycle time for the robot is 40 seconds. If the robot could reduce each weld to 1.8 seconds, the total cycle time would be 36 seconds. That 4-second savings might allow the line to produce one extra car per hour. Over a year, that could be thousands of extra cars. |
In painting, articulated robots move along the car body and apply paint. Cycle time is important because the paint must be applied evenly and without drips. If the robot moves too fast, the paint quality suffers. If it moves too slowly, the line slows down. Therefore, painting robots are programmed to move at the fastest speed that still meets quality standards. Cycle times for painting a full car body might be 60 to 120 seconds. |
In final assembly, articulated robots are used to install seats, windshields, batteries, and other components. Cycle times vary widely. Installing a seat might take 20 seconds. Installing a windshield might take 30 seconds. Installing a battery pack in an electric vehicle might take 60 seconds. In all these cases, the robot must be fast enough to meet the line takt time, which is the time between two consecutive cars coming off the line. If the takt time is 60 seconds, every station must complete its work in 60 seconds or less. |
SCARA robots are also used in automotive assembly for small parts, such as screws, clips, and connectors. They are faster than articulated robots but have lower payloads. Delta robots are rarely used in automotive assembly because the parts are too heavy. However, Delta robots are sometimes used in automotive electronics, such as assembling sensors and control modules. |
Cartesian robots are used in automotive for tasks such as dispensing adhesives, sealing, and inspection. They can be very fast over large areas. For example, a Cartesian robot might move a camera along a car body to inspect for defects. The cycle time might be 30 seconds per car. This is faster than a human inspector and more consistent. |
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6. Cycle Time in Pharmaceutical and Medical Device Production |
Pharmaceutical production requires high precision, cleanliness, and documentation. Cycle time is important, but it must not compromise quality. Delta robots are used for sorting and packaging pills, capsules, and vials. They can achieve cycle times of 0.3 to 0.6 seconds per item. They are often used in blister packaging lines, where they pick pills from a hopper and place them into blister pockets. They are also used in vial filling lines, where they pick vials from a conveyor and place them into trays. |
SCARA robots are used for more complex tasks, such as assembling syringes, inhalers, and diagnostic devices. They can achieve cycle times of 1 to 2 seconds. They are often used in cleanrooms, where they must meet strict particle and microbial limits. They are designed with smooth surfaces, sealed joints, and cleanroom-compatible lubricants. |
Articulated robots are used for heavier tasks, such as handling trays of vials, loading and unloading autoclaves, and palletizing boxes of medicine. Their cycle times are slower, often 3 to 6 seconds. However, they can carry heavy payloads and can work in large work areas. |
In medical device production, cycle time is critical for products such as catheters, stents, and orthopedic implants. These products are often assembled by hand because they are delicate and complex. However, robots are increasingly used for tasks such as placing tiny components, applying adhesives, and inspecting parts. Delta robots are used for high-speed inspection, where they pick and place parts under a camera. SCARA robots are used for assembly, where they insert and tighten small screws. Articulated robots are used for polishing and finishing implants. |
In all these applications, cycle time must be balanced with validation. The robot must be validated to ensure that it consistently meets specifications. If the cycle time is too fast, the robot may not have enough time to verify that the task was completed correctly. Therefore, cycle time is often set to the fastest speed that still allows for reliable quality control. |
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7. Cycle Time in Logistics and Warehousing |
Logistics and warehousing have seen explosive growth in robot use, driven by e-commerce. Cycle time is the key metric because warehouses must process thousands of orders per hour. Delta robots are used for high-speed sorting of small items, such as books, electronics, and cosmetics. They can sort 200 to 400 items per minute. That is a cycle time of 0.15 to 0.3 seconds per item. They are often used in cross-belt sorters and tilt-tray sorters. |
SCARA robots are used for picking items from shelves and placing them into bins. They can achieve cycle times of 1 to 2 seconds. They are often used in goods-to-person systems, where a robot brings a shelf to a picking station, and a SCARA robot picks the ordered items. They are also used in packing stations, where they place items into boxes. |
Cartesian robots are used for palletizing and depalletizing. They can pick up entire layers of boxes and place them onto pallets. Cycle times are often 5 to 10 seconds per layer. Articulated robots are used for mixed palletizing, where they pick boxes of different sizes and weights and stack them onto a pallet. Their cycle times are slower, often 4 to 8 seconds per box, but they are more flexible. |
In logistics, cycle time is directly linked to labor cost. A warehouse that can process 10,000 orders per hour with robots might need only 20 workers, while a manual warehouse might need 200 workers. The faster the robots, the fewer workers are needed, and the lower the cost per order. This is why logistics companies are willing to invest in the fastest robots available. |
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8. Cycle Time in Plastics and Injection Molding |
Injection molding is a fast, repetitive process. A plastic part can be molded in a few seconds. The robot must remove the part from the mold and place it on a conveyor or into a box. Cycle time is critical because the robot must keep up with the molding machine. If the robot is too slow, the molding machine must wait, which wastes energy and reduces productivity. |
Articulated robots are commonly used for injection molding because they can reach into the mold, grab the part, and pull it out. They can also perform secondary tasks, such as cutting sprues, inspecting parts, and placing inserts. Cycle times for part removal are often 3 to 6 seconds. SCARA robots are sometimes used for smaller parts, with cycle times of 1 to 3 seconds. Cartesian robots are used for simple part removal, with cycle times of 2 to 4 seconds. |
Delta robots are rarely used in injection molding because the parts are often too heavy or too hot. However, Delta robots are sometimes used for high-speed inspection of small plastic parts, such as caps and closures. They can inspect 300 parts per minute. |
In plastics manufacturing, cycle time also affects energy consumption. The molding machine uses a lot of energy to heat and inject plastic. If the robot is slow, the machine must stay open longer, which wastes heat. Therefore, reducing robot cycle time can reduce energy costs. This is an important consideration for sustainability. |
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9. Cycle Time in Metalworking and Machining |
Metalworking and machining involve cutting, drilling, milling, and turning metal parts. Robots are used for machine tending, which means loading and unloading workpieces from machines. Cycle time is important because the robot must keep the machine running. If the robot is too slow, the machine sits idle, which is expensive. |
Articulated robots are the most common choice for machine tending because they can carry heavy workpieces and can reach into machines. Cycle times for loading and unloading are often 5 to 15 seconds, depending on the size and weight of the part. SCARA robots are used for smaller parts, with cycle times of 2 to 5 seconds. Cartesian robots are used for simple, repetitive tasks, such as moving parts from a conveyor to a machine. Their cycle times are often 3 to 8 seconds. |
Delta robots are rarely used in metalworking because the parts are too heavy. However, Delta robots are sometimes used for high-speed sorting of small metal parts, such as screws and bolts. They can sort 500 parts per minute. |
In metalworking, cycle time must be balanced with precision. The robot must place the workpiece into the machine with high accuracy. If the robot is too fast, it may not seat the part correctly, which can cause tool breakage or poor quality. Therefore, the robot is often programmed to slow down at the final approach. This adds a small amount of time but ensures reliability. |
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10. Cycle Time in Glass, Solar, and Battery Manufacturing |
Glass manufacturing involves handling large, heavy, and fragile sheets. Robots are used to move glass sheets from conveyor to conveyor, or from conveyor to rack. Cycle time is important because the glass must be moved quickly to avoid bottlenecks. Articulated robots are commonly used because they can carry heavy loads and can reach large areas. Cycle times are often 5 to 10 seconds per sheet. Cartesian robots are also used, especially for large sheets, with cycle times of 4 to 8 seconds. |
Solar panel manufacturing involves assembling solar cells into panels. Delta robots are used for high-speed pick-and-place of solar cells. They can place 200 to 400 cells per minute. That is a cycle time of 0.15 to 0.3 seconds per cell. SCARA robots are used for soldering and bonding, with cycle times of 1 to 2 seconds. Articulated robots are used for framing and palletizing, with cycle times of 4 to 8 seconds. |
Battery manufacturing is one of the fastest-growing applications for robots. Lithium-ion batteries are made of many cells, modules, and packs. Delta robots are used for high-speed sorting and placing of small cells. SCARA robots are used for assembling modules, with cycle times of 1 to 3 seconds. Articulated robots are used for pack assembly and palletizing, with cycle times of 5 to 10 seconds. In battery manufacturing, cycle time is critical because the demand for batteries is enormous. A single electric vehicle battery pack may contain thousands of cells. If each cell takes 0.1 seconds too long to place, the total assembly time increases by minutes. |
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11. Cycle Time in Consumer Goods and Appliances |
Consumer goods and appliances are produced in large volumes. Robots are used for assembly, inspection, and packaging. Delta robots are used for high-speed pick-and-place of small parts, such as buttons, knobs, and switches. They can achieve cycle times of 0.2 to 0.5 seconds. SCARA robots are used for assembling larger parts, such as motors, gears, and housings. They can achieve cycle times of 1 to 2 seconds. Articulated robots are used for heavy tasks, such as moving appliances and palletizing. Their cycle times are often 4 to 8 seconds. |
Consider a factory that makes electric toothbrushes. A Delta robot might pick the handle and place it into a package. The cycle time might be 0.4 seconds. A SCARA robot might assemble the brush head onto the handle. The cycle time might be 1.5 seconds. An articulated robot might palletize the packaged toothbrushes. The cycle time might be 5 seconds per box. In all these cases, cycle time determines how many toothbrushes can be produced per shift. |
In appliance manufacturing, cycle time also affects quality. If the robot moves too fast, it may drop or damage the part. Therefore, the robot is often equipped with force sensors and vision systems to ensure that the part is handled correctly. These sensors add a small amount of time but prevent costly defects. |
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12. Cycle Time in Agriculture and Food Processing |
Agriculture and food processing are increasingly using robots. Delta robots are used for high-speed sorting of fruits, vegetables, and nuts. They can sort 200 to 400 items per minute. For example, a Delta robot might sort apples by size and color. The cycle time might be 0.3 seconds per apple. SCARA robots are used for packing produce into boxes or bags. They can achieve cycle times of 1 to 2 seconds. Articulated robots are used for heavy tasks, such as picking up crates and palletizing. Their cycle times are often 4 to 8 seconds. |
In meat processing, robots are used for cutting, deboning, and packaging. Cycle time is important because meat is perishable and must be processed quickly. Articulated robots are often used because they can handle heavy cuts and can work in cold environments. Cycle times vary widely, from 2 seconds for simple cuts to 10 seconds for complex deboning. |
In dairy processing, robots are used for milking, feeding, and cleaning. Cycle time is important because cows must be milked at regular intervals. A milking robot might take 5 to 10 minutes per cow, but it can work 24 hours a day. This is not a fast cycle time compared to a Delta robot, but it is fast enough to replace manual labor. |
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13. Cycle Time in Laboratory Automation and Life Sciences |
Laboratory automation uses robots to handle test tubes, petri dishes, and microplates. Cycle time is critical because laboratories often need to process thousands of samples per day. Delta robots are used for high-speed picking and placing of microplates. They can achieve cycle times of 0.5 to 1 second. SCARA robots are used for pipetting and liquid handling. They can achieve cycle times of 1 to 3 seconds. Articulated robots are used for moving larger containers and operating instruments. Their cycle times are often 3 to 6 seconds. |
In drug discovery, robots are used to screen thousands of compounds. A Delta robot might move a microplate from a stacker to a reader. The cycle time might be 0.8 seconds. If the robot is too slow, the screening process takes longer, which delays the discovery of new drugs. In clinical diagnostics, robots are used to prepare samples for analysis. Cycle time is important because patients need results quickly. A SCARA robot might move a test tube from a rack to a centrifuge. The cycle time might be 2 seconds. |
In life sciences, cycle time must be balanced with precision and sterility. The robot must not contaminate the samples. Therefore, the robot is often enclosed in a cleanroom or a biosafety cabinet. It must also be able to work with small volumes, often in the microliter range. This requires high precision, which may limit speed. |
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14. Cycle Time in 3D Printing and Additive Manufacturing |
3D printing, also called additive manufacturing, builds parts layer by layer. Robots are used for post-processing, such as removing support structures, sanding, and polishing. Cycle time is important because 3D printing can be slow, and post-processing can become a bottleneck. Delta robots are used for high-speed pick-and-place of small printed parts. They can achieve cycle times of 0.3 to 0.6 seconds. SCARA robots are used for removing support structures and cleaning parts. They can achieve cycle times of 1 to 3 seconds. Articulated robots are used for larger parts and for tasks such as sanding and painting. Their cycle times are often 5 to 15 seconds. |
In some advanced 3D printing systems, robots are used to move the print head or the build plate. For example, a Cartesian robot might move a print head over a large bed. The cycle time for each layer might be 1 to 5 seconds. If the robot is faster, the print can be completed sooner. However, the speed is often limited by the printing process itself, such as the flow rate of the material. |
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15. Cycle Time in Textile, Paper, and Tobacco Industries |
Textile manufacturing involves spinning, weaving, knitting, and finishing. Robots are used for handling yarn bobbins, fabric rolls, and finished garments. Delta robots are used for high-speed sorting of small items, such as buttons and zippers. SCARA robots are used for sewing and assembly, with cycle times of 1 to 3 seconds. Articulated robots are used for moving heavy fabric rolls and palletizing, with cycle times of 5 to 10 seconds. |
Paper manufacturing involves handling large rolls of paper. Articulated robots are used to move rolls from machine to machine. Cycle times are often 10 to 20 seconds. Cartesian robots are used for cutting and stacking paper, with cycle times of 2 to 5 seconds. |
Tobacco manufacturing involves high-speed production of cigarettes. Delta robots are used for picking and placing cigarette packs into cartons. They can achieve cycle times of 0.2 to 0.4 seconds. SCARA robots are used for inspecting and sorting cigarettes, with cycle times of 0.5 to 1 second. Articulated robots are used for palletizing cartons, with cycle times of 4 to 8 seconds. |
In all these industries, cycle time is important because margins are thin and production volumes are high. Even a small improvement in cycle time can lead to significant cost savings. |
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16. Cycle Time in Cosmetics and Personal Care |
Cosmetics and personal care products are produced in large volumes. Robots are used for filling, capping, labeling, and packaging. Delta robots are used for high-speed pick-and-place of small items, such as lipsticks, compacts, and bottles. They can achieve cycle times of 0.3 to 0.6 seconds. SCARA robots are used for assembling components, such as pumps and caps. They can achieve cycle times of 1 to 2 seconds. Articulated robots are used for palletizing and case packing, with cycle times of 4 to 8 seconds. |
In cosmetics, cycle time must be balanced with hygiene. The robot must not contaminate the product. Therefore, the robot is often made of stainless steel and uses food-grade lubricants. It may also be enclosed in a cleanroom. The cycle time is important, but it never comes before product safety. |
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17. Cycle Time in Aerospace and Defense |
Aerospace and defense manufacturing involves complex, high-value parts. Cycle time is important, but it is often less critical than precision and quality. Articulated robots are commonly used for drilling, riveting, and inspection. They can carry heavy tools and can work on large structures. Cycle times are often 10 to 60 seconds per operation. Delta robots are rarely used because the parts are too heavy. SCARA robots are used for small parts, such as electronic components, with cycle times of 1 to 3 seconds. Cartesian robots are used for large tasks, such as moving wings and fuselages, with cycle times of 30 to 120 seconds. |
In aerospace, a single mistake can be catastrophic. Therefore, the robot must be highly accurate and reliable. The cycle time is often set to the fastest speed that still allows for 100 percent inspection. This may mean that the robot moves slower than its maximum speed, but it ensures that every part meets specifications. |
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18. Cycle Time in Construction and Building Materials |
Construction and building materials manufacturing involves heavy, bulky products. Robots are used for tasks such as cutting, drilling, and palletizing. Articulated robots are commonly used because they can carry heavy loads. Cycle times are often 10 to 30 seconds per part. Cartesian robots are used for large work areas, such as cutting panels, with cycle times of 5 to 15 seconds. Delta robots are rarely used because the parts are too heavy. SCARA robots are used for small parts, such as fasteners, with cycle times of 1 to 3 seconds. |
In construction, cycle time is important because projects have tight schedules. However, the robot must also be able to work in harsh environments, such as dust, rain, and extreme temperatures. This may limit the speed. For example, a robot that is exposed to dust may need slower movements to avoid damaging its joints. |
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19. Cycle Time in Recycling and Waste Management |
Recycling and waste management involve sorting mixed materials. Robots are used to pick specific items from a conveyor belt. Delta robots are used for high-speed sorting of small items, such as plastic bottles and aluminum cans. They can achieve cycle times of 0.3 to 0.6 seconds. SCARA robots are used for sorting larger items, with cycle times of 1 to 3 seconds. Articulated robots are used for moving heavy bins and palletizing, with cycle times of 5 to 10 seconds. |
In recycling, cycle time is critical because the conveyor belt moves continuously. If the robot is too slow, it will miss items, and the recycling rate will drop. Therefore, recycling facilities often use multiple Delta robots in parallel to keep up with the belt speed. They also use advanced vision systems to identify and sort materials quickly. |
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20. Cycle Time in Art and Entertainment |
Art and entertainment use robots for tasks such as painting, sculpting, and performing. Cycle time is less critical in these applications because the goal is creativity, not mass production. Articulated robots are commonly used because they can make complex, smooth movements. Cycle times can be minutes or even hours. Delta robots are used for high-speed drawing or painting, with cycle times of 0.1 to 0.5 seconds per stroke. SCARA robots are used for small tasks, such as engraving, with cycle times of 1 to 5 seconds. |
In entertainment, robots are used in theme parks, shows, and movies. Cycle time is important for synchronization. For example, a robot might need to move in sync with music or with other robots. The cycle time must be precise, often within milliseconds. This requires high-performance controllers and precise motion planning. |
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21. Factors That Influence Cycle Time Beyond Robot Type |
Robot type is not the only factor that influences cycle time. Many other factors come into play. The distance traveled is one. A short move takes less time than a long move. The payload is another. A heavy payload requires more torque and acceleration time. The gripper is another. A slow gripper can add time to each cycle. The control software is another. Advanced motion planning can reduce cycle time by optimizing the path and reducing vibration. The vision system is another. A fast vision system can locate parts quickly, while a slow one can add time. The workcell layout is another. A well-designed workcell can reduce travel distances and improve cycle time. |
Environmental factors also matter. Temperature, humidity, and dust can affect robot performance. In food processing, washdown requirements may limit the speed. In cleanrooms, particle generation may limit the speed. In hazardous environments, safety requirements may limit the speed. |
Maintenance also matters. A well-maintained robot runs faster and more reliably. A poorly maintained robot may have worn joints, which reduce speed and accuracy. Therefore, cycle time is not just a design parameter. It is also a maintenance parameter. |
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22. Trade-offs: Cycle Time vs Payload, Precision, and Cost |
Cycle time cannot be optimized in isolation. There are always trade-offs. The most common trade-off is between cycle time and payload. Delta robots are very fast but can only carry light payloads. Articulated robots are slower but can carry heavy payloads. If an application requires both high speed and heavy payload, there is no perfect robot. The engineer must choose the best compromise. Sometimes, the solution is to use multiple robots. For example, two Delta robots can each carry half the payload and together achieve the required throughput. Sometimes, the solution is to use a larger articulated robot with a faster controller. |
Another trade-off is between cycle time and precision. Faster movements can cause vibration, which reduces precision. Therefore, high-precision applications often require slower speeds. For example, a robot that places tiny electronic components must move slowly enough to avoid overshoot. A robot that welds car bodies must move slowly enough to maintain weld quality. |
Another trade-off is between cycle time and cost. Faster robots are often more expensive. They require more powerful motors, stiffer structures, and advanced controllers. They may also require more maintenance. Therefore, the engineer must decide whether the extra speed is worth the extra cost. In many cases, the answer is yes, because the extra speed leads to higher throughput and lower cost per unit. But in some cases, the answer is no, because the application does not require high speed. |
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23. Measuring and Improving Cycle Time |
Measuring cycle time is straightforward. The engineer uses a stopwatch or a software timer to measure the time from the start of the cycle to the end. However, it is important to measure the cycle time under realistic conditions. The payload should be the same as in production. The distances should be the same. The gripper should be the same. The vision system should be the same. Otherwise, the measured cycle time may not be accurate. |
Improving cycle time can be done in many ways. One way is to reduce the distance traveled. This can be done by rearranging the workcell. Another way is to reduce the payload. This can be done by using a lighter gripper or by picking up fewer parts at a time. Another way is to improve the motion profile. This can be done by using smoother acceleration and deceleration curves. Another way is to use a faster gripper. Another way is to use a faster vision system. Another way is to use a more powerful robot. Another way is to use multiple robots. |
In many cases, the biggest improvement comes from optimizing the entire process, not just the robot. For example, if the conveyor is moving too fast, the robot may have to wait. If the conveyor is moving too slow, the robot may be idle. Therefore, the engineer must balance the entire system. This is called line balancing. Line balancing is the process of adjusting the speed of each station so that the entire line runs smoothly. Cycle time is a key input to line balancing. |
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24. Detailed Summary and Key Takeaways |
Cycle time is a fundamental performance metric in industrial robotics. It measures how long a robot takes to complete one full work cycle. Delta robots achieve the fastest cycle times, often measured in tenths of a second. They are followed by SCARA robots, which are fast and precise. Cartesian and articulated robots are generally slower but can carry higher payloads. The speed hierarchy is: Delta, SCARA, Cartesian, articulated. However, this hierarchy is not absolute. It depends on the application, the payload, the distance, and the environment. |
In food and beverage packaging, Delta robots dominate because they are fast and hygienic. They can pick and place hundreds of items per minute. SCARA robots are used for tasks that require more force or precision. Cartesian and articulated robots are used for palletizing and heavy tasks. In electronics and semiconductor manufacturing, Delta and SCARA robots are used for high-speed assembly and inspection. Cycle times can be as low as 0.2 seconds per component. In automotive assembly, articulated robots dominate because they can carry heavy payloads and perform complex tasks. Cycle times are often measured in seconds or tens of seconds. In pharmaceutical and medical device production, Delta and SCARA robots are used for high-speed sorting and assembly, while articulated robots are used for heavy tasks. Cycle time must be balanced with cleanliness and validation. |
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In logistics and warehousing, Delta robots are used for high-speed sorting, while SCARA robots are used for picking and packing. Cartesian and articulated robots are used for palletizing. Cycle time directly affects labor cost and throughput. In plastics and injection molding, articulated robots are used for part removal, with cycle times of a few seconds. In metalworking and machining, articulated robots are used for machine tending, with cycle times of 5 to 15 seconds. In glass, solar, and battery manufacturing, Delta robots are used for high-speed handling of small parts, while articulated robots are used for heavy tasks. In consumer goods and appliances, Delta and SCARA robots are used for assembly, while articulated robots are used for palletizing. In agriculture and food processing, Delta robots are used for sorting, while articulated robots are used for heavy tasks. In laboratory automation, Delta and SCARA robots are used for high-speed sample handling. In 3D printing, robots are used for post-processing, with cycle times of a few seconds to minutes. In textile, paper, and tobacco industries, Delta robots are used for high-speed packaging, while articulated robots are used for heavy tasks. In cosmetics and personal care, Delta and SCARA robots are used for filling and assembly. In aerospace and defense, articulated robots are used for complex tasks, with cycle times of tens of seconds. In construction and building materials, articulated robots are used for heavy tasks. In recycling and waste management, Delta robots are used for high-speed sorting. In art and entertainment, robots are used for creative tasks, with cycle times that vary widely. |
The key takeaway is that cycle time is not just a number. It is a design parameter that must be balanced with payload, precision, reach, cost, and reliability. The fastest robot is not always the best robot. The best robot is the one that meets the required cycle time while also meeting all other requirements. Engineers must consider the entire workcell, including the conveyor, the gripper, the vision system, and the control software. They must also consider maintenance, environment, and safety. By understanding cycle time and its trade-offs, engineers can design robotic systems that are fast, reliable, and cost-effective. This concludes Chapter 24. The next chapter will explore repeatability and accuracy, another critical performance metric in industrial robotics. |
cs@easiersoft.com