Datasheets for dispensing equipment usually highlight a single accuracy figure, such as plus or minus one per cent of the target volume. That number is useful, but it is often measured under controlled laboratory conditions with an ideal fluid, a steady temperature and a fresh setup. On a real production line, many other factors decide whether a system delivers consistent results. For manufacturers investing in precision dispensing, looking beyond the nominal specification helps reveal how a system will perform across shifts, materials and months of use.
Repeatability Over Long Production Runs
A system may hit its target on the first hundred shots but drift over thousands. Evaluating repeatability means looking at how results hold up over time, through checks like these:
- Measuring shot weight or volume across an entire shift, not just a short trial.
- Calculating process capability indices, such as Cpk, to see how consistently results stay within tolerance.
- Comparing the first shots after start-up with those later in the run.
- Recording how often recalibration is needed to stay on target.
Performance Across Different Fluid Properties
Accuracy figures are often based on water or a reference fluid, while production materials can behave very differently. When assessing a system, it helps to test with your own materials and look at factors such as these:
- High-viscosity adhesives, sealants or pastes that resist flow.
- Fluids containing fillers or particles that can settle or cause wear.
- Moisture-sensitive or fast-curing materials that change over the course of a shift.
- Shear-sensitive fluids whose properties alter when pumped or pressurised.
- Materials prone to trapping air, which can cause voids or inconsistent shots.
Stability of the Fluid Supply
Dispensing results depend heavily on how steadily fluid reaches the valve or pump. Many systems draw material from pressure tanks or cartridges, and variations in supply can show up as shot-to-shot differences. Points worth assessing include the following:
- How consistently supply pressure is maintained as the reservoir empties.
- Whether pressure regulators respond quickly to changes in demand.
- How changes of tank, cartridge or syringe affect the first shots afterwards.
- Whether feed lines are short and sized to limit pressure drops.
Sensitivity to Temperature and Environment
Viscosity often changes with temperature, which can alter flow rates and shot sizes. To understand how a system copes with real conditions, consider checks like these:
- Running trials at different ambient temperatures across the day.
- Assessing whether heated or temperature-controlled components are needed.
- Checking how humidity affects moisture-sensitive materials.
- Noting whether nearby equipment, such as curing ovens or lamps, warms the dispensing area.
- Monitoring results after breaks, when material may have cooled in the lines.
Shot Cut-Off and Placement Quality
Volume accuracy alone does not guarantee a clean result on the part. The way each shot begins and ends can be just as important, so evaluate details such as these:
- Stringing, tailing or drips at the end of each dispense.
- Consistency of bead width and shape along a programmed path.
- Positional accuracy when combined with robots or motion systems.
- Satellite droplets or splatter with jetting valves.
Maintenance Needs and Long-Term Drift
Wear and contamination can gradually change how a system performs. Looking at maintenance requirements helps estimate real-world consistency, including points like these:
- How often seals, nozzles or pump components need replacing.
- Whether performance drifts as parts wear between service intervals.
- How easily the system can be cleaned without affecting calibration.
- The availability of spare parts and technical support.
Testing Under Your Own Conditions
Nominal accuracy is a starting point, not a guarantee. Running trials with your own materials, cycle times and production environment, and tracking results over an extended period, gives a clearer picture of whether a dispensing system will meet your quality requirements day after day.
Need to test a dispensing setup with your own materials? Contact Unicontrols today and let us assist you..
