Robot Payload and Wrist Moment Rating: The Offset Load Problem
The Robot That Faulted Under Load We mounted a gripper on a 6-axis robot. The payload spec said “10 kg.” The gripper + part weighed 8 kg (under the 10 kg). On the floor, the…
Author: JUMI
Pneumatic Air Consumption Calculation: Cylinders, Ejectors, Compressor Sizing
The Compressor That Couldn’t Keep Up: Calculating Air Demand, Not Guessing The plant air pressure dropped every time a new machine cycled. The compressor ran constantly but couldn’t maintain 6 bar. The customer thought the…
Sensor Resolution vs Repeatability vs Accuracy: Gauge R&R
The Sensor That Read 0.05 mm Differently Every Time: Repeatability vs Accuracy A laser displacement sensor measuring part height on a check station. The same part, measured 10 times, gave 10 readings: 12.00, 12.03, 11.98,…
Machine Guard Material Selection: Polycarbonate, Mesh and Steel
The Guard That Cracked When a Part Flew Out: Impact Resistance, Not Decoration A machining cell with a clear polycarbonate guard. The door was 5 mm thick, bolted in an aluminum frame. A broken tool…
Servo Loop Tuning Basics: Gain, Following Error and Resonance
The Axis That Overshot Every Move: Settling Time, Not Tuning A positioning axis on a dispensing machine. Every move, the carriage overshot the target by 0.2 mm, then settled back. The settle time was 200…
Ball Screw Critical Speed and DN Ratio: Long Screw Whine and Resonance
The Screw That Whined at 3000 rpm: Ball Screw Noise, Diagnosed A rolled ball screw, Ø25 mm, 10 mm lead. At 1000 rpm it was quiet. At 3000 rpm it whined — a high-pitched tone…
PLC Scan Time and Motion Control: Discrete vs Continuous Motion
The Motion That Jittered at High Speed: Servo Tuning, From Symptom to Fix A linear axis on a gantry. At low speed (100 mm/s), motion was smooth. At 500 mm/s, the carriage vibrated — a…
Coupling Misalignment and Shaft Alignment: Parallel, Angular, Axial
The Coupling That Failed in 30 Days: Misalignment, Not Torque A servo motor driving a ball screw through a jaw coupling (aluminum hubs, polyurethane spider). After 30 days, the spider cracked. The motor lost torque…
Vacuum System Maintenance: Filter, Cups, Leaks and Ejector
The Vacuum That Lost Grip After Lunch: Degradation Over a Shift A vacuum gripper running a 3-shift cell. Morning shift: perfect. Afternoon shift: dropping parts. Night shift: nothing holds. The customer thought the cups were…
Control Relay vs Safety Relay: Forced-Guided Contacts and Monitoring
The Relay That Welded Its Contacts: Sizing a Relay for an Inductive Load A 24 V DC relay switching a solenoid valve coil. The relay closed, the valve clicked, the relay contacts welded shut. The…
Conveyor Side Guide Design: Adjustable Width, Corners and Hold-Down
Why the Boxes Jammed at the Corner: Conveyor Flow, Explained A Z-shaped conveyor line. Boxes came in on a straight section, then turned 90° onto a cross-conveyor. Every 20th box jammed at the corner. The…
Robot Tool Changer Selection: Fail-Safe Lock, Sensors and Payload
The Tool Changer That Dropped the Gripper: What Holds It Together A robot tool changer. The automatic coupling that switches between a gripper and a vacuum cup. It dropped the gripper mid-cycle — the tool…
Flow Control Meter-In vs Meter-Out: Cylinder Speed Control
The Cylinder That Ran Away on Retract: Reading the Pneumatic Circuit A double-acting cylinder, Ø63 mm bore, 200 mm stroke. Extend was controlled — a flow control on the cap end slowed it to a…
Servo Motor Holding Brake: Vertical Axes, Torque and Sequence
The Vertical Axis That Dropped on Power Loss We used a servo motor (without a holding brake) to drive a vertical Z-axis. The axis moved up and down. On the bench, it held position when…
Linear Shaft vs Profile Rail: Sag Calculation and When to Use Which
The Linear Shaft That Sagged: Beam Deflection, by the Numbers A Ø20 mm hardened linear shaft, 800 mm long, supported at both ends. A carriage carrying 20 kg rode on two linear bearings. At mid-span,…
