Views: 1 Author: Site Editor Publish Time: 2026-10-15 Origin: Site
A factory acceptance test, or FAT, is your last structured chance to find specification gaps before a sigma mixer is packed and shipped. The best FAT does more than prove that the motor turns. It checks the approved drawing, materials, controls, safeguards, vacuum or thermal functions, discharge system, and documentation against written acceptance criteria. A short, witnessed test can prevent expensive changes after installation.
l Freeze approved specification and FAT protocol prior to test date.
l Check identity, dimensions, product-contact materials, fabrication, mechanical action, services, controls and safeguards in a logical sequence.
l Use measurable pass criteria for speed, temperature, vacuum, leakage, interlocks and for discharge rather than accepting a general demonstration of each.
Record all deviations including owner, correction action, required evidence and closure date prior to shipment release.
This is where we start the FAT with paperwork instead of the start button. We need the latest signed copy of the supplier’s specification and general arrangement drawings plus the process and instrumentation diagrams for certain parts of the plant as well as the electrical standard. We also need to include the hazardous area classification and the utility conditions. The agreed recipe or substitute test material, test sequence, measuring instruments and pass/fail limits for each test also need to be included. Remember one can always argue against a requirement that has not been detailed in the protocol based on memory!
Determine whether the test in question is to be conducted as a no-load mechanical run, a water-based function test or a loaded process trial. An empty mechanical run may reveal issues such as noise, incorrect rotation, vibration, interlocks and basic control faults. However an empty mechanical run does not allow determination of critical parameters such as torque, mixing time, heat removal, vacuum when processing with material and discharge of sticky material. List the limitations and specify the relevant performance checks that will be conducted during site acceptance testing.
Karvil Machinery lists customizable mixer materials, heating and cooling methods, vacuum systems, motors, controls, and discharge arrangements across its Sigma mixer products. Your FAT checklist must follow the purchased configuration. Testing a tilting machine as if it had screw discharge, or checking a standard cabinet against an explosion-proof order, misses the actual risk.
Walk around the machine before power is applied. Match the nameplate, model, serial number, voltage, frequency, phase, motor ratings, total and working volumes, and major purchased components to the order. Measure critical footprint, inlet, outlet, platform, and utility connection locations against the approved drawing. A misplaced nozzle may look minor in the factory yet force piping changes at your site.
Confirm the material grade for the chamber, blades, cover, shaft-contact areas, and discharge path using the agreed certificates. Inspect welds, corners, polish, drainability, and areas where residue could collect. For food-contact duty, request the applicable material and compliance records and verify that seals, lubricants, and cleaning access match the hygiene plan. Do not infer compliance from a polished appearance.
Rotate or jog the blades only under the supplier's safe procedure. Check the documented clearances at the shell and end plates, blade condition, fasteners, bearing arrangement, seal installation, guards, and gearbox oil level. Any manual measurement near the blades requires full energy isolation. A cover interlock is useful, but it is not a substitute for lockout during inspection.
Test run each function from the normal operation of the functions from the operator controls and record the feedback from the panel. Evidence of operation could be recording of actual fast and slow blade speeds at set points, motor current, gearbox noise, bearing temperature trend, vacuum level and hold time, temperature indication, and evidence of heating or cooling and lid motion and discharge speed or tilting time etc. Where a value has been recorded using a calibrated instrument then that value is the evidence of that parameter’s operation.
FAT area | Example evidence | Typical concern |
Blade drive | Direction, rpm at set points, current, noise | Wrong rotation or weak low-speed duty |
Vacuum | Achieved level, hold period, leak trend | Seal leakage or undersized connections |
Thermal system | Sensor agreement, circulation, alarms | Slow response or unsafe set limits |
Discharge | Full motion, speed range, reversal, limit switches | Residue, pinch point, or unstable movement |
Controls | Mode changes, recipes, alarms, data, power recovery | Unclear state or lost settings |
For a vacuum machine, check the pump, piping, buffer tank, valves, gauge, cover gasket, shaft seals, and alarm logic together. Record the stable vacuum and the pressure rise during an agreed hold period. A strong pump cannot compensate for poor sealing. For the jacket, confirm the medium, allowable pressure, direction of circulation, sensor location, over-temperature response, and whether blades or screw barrel are included. Never heat a jacket without the approved medium, venting, and operating procedure.
Check for smooth operation over the full travel of the tilting discharge, to stop at limits and return without drift. Also check for adequate stability of the machine and the guarded pinch zones. For screw extrusion check for forward and reverse rotation, check the speed range, interlocks and check for cleaning access. The no-load screw test only confirms motion, but not the pressure and residue which is expected with the production of a product. Thus a loaded discharge test has to be conducted for site acceptance test, which – unfortunately – cannot be simulated with the FAT material, which is not representative.
Deliberately test safety functions and reset them afterwards. Test all emergency stops, open the lid of the container in test status, check protective guarding of exposed transmissions, and verify that the mixer does not start up again unexpectedly when power is restored. Test alarm messages, permitted sequences of functions, manual mode and automatic mode as well as behavior in case of failure of sensors which are specified. Further, certificates for Hazardous-area orders have to be presented and equipment marking as well as cable entries, earthing and housing of containers have to be checked against the agreed classification.
This test setup represents the standard configuration for the 100 L vacuum sigma kneader with extruder discharge. The following components are included in the standard setup: 15 kW main drive, 5.5 kW extrusion drive, variable blade speed, vacuum level up to -0.09 MPa, heating/cooling, lid limit switch, emergency-stop safety relay, 24 V control circuit. Each component or option purchased must be tested in a separate test step with corresponding results.
Verify the delivered document set against the contract after the test. Such documents are signed FAT record, General Arrangement drawing, Electrical schematic, Bill of materials, English language Operation and Maintenance manual, Certificates, Recommended spare parts list, Lubrication schedule and Packing list. The documents delivered with the sold equipment by Karvil Machinery are English manual and electrical diagram. Warranty is given for 1 year. Remote technical service is given via internet for long period of time. Terms and conditions for your order should be specified in your order in any case when general information is provided.
List all punch register deviations with following information: clear description, relevant specification, agreed solution, responsible person, deadline. Differentiate between items that prevent shipment and minor documentation deviations. Approval for shipment of critical items only after closure of said items or written concession for remaining deviation.
Use the official Karvil Machinery website to verify current contact and product information, review application examples, and request relevant technical downloads. Send your FAT checklist with the inquiry so test access, materials, instruments, witnesses, and documentation are priced and scheduled from the start.
Q1: Is a no-load FAT enough for a sigma mixer?
This information is useful for defining the construction, motion, controls and protection aspects of a mixer but does not enable any conclusion to be reached concerning loaded torque, process temperature, product behavior under vacuum, mixing efficiency or difficult unloading situations.
Q2: Who should attend the FAT?
A: The people to include would be to assess process needs, mechanical and electrical construction and controls, safety and commercial scope. If remote witnessing is to be used then agreement of camera views and data would be required prior to the session.
Q3: What measuring tools should be calibrated?
A: Use the instruments listed above for the acceptance values to check a tachometer, temperature probe, pressure or vacuum reference, electrical meter, and all your dimensional tools.
Q4: Can water replace the real material during FAT?
Q: Can water test check for leaks, for circulation, for valves, for some instruments? A: Yes, water test can check for leaks, for circulation, for valves, for some instruments. However, water test cannot show torque, shear heating, wetting, vacuum release, discharge of high-viscosity formulations.
Q5: What happens when an FAT item fails?
A: Record the issue, agree a repair with retest evidence, assign owner and date and withhold shipment approval for critical parts until closure or formal concession.
