Automatic Screw Feeder Selection for Thai Factories | RFP and FAT/SAT

Selecting an automatic screw feeder takes more than comparing the advertised feed rate and nominal screw diameter. In a Thai factory, head geometry, captive washers, coating, oil, foreign parts, pick-up posture, distance to the driver, changeovers and local maintenance all affect whether the system will run reliably. This guide helps engineering and purchasing teams compare screw presenters, air-fed systems, bowl feeders and step feeders. It turns the comparison into a sample trial, a request for proposal (RFP), and documented factory and site acceptance tests (FAT/SAT).

First define where automatic screw feeding is complete

A requirement that simply says “feed screws automatically” leaves the supplier’s scope open to interpretation. Does delivery end when a screw is oriented at the outlet, presented at a pick-up nest, transported to the driver nosepiece, or acknowledged by a connected tightening system? A feeder may work perfectly in a demonstration while the installed line fails at the hose, sensor, nosepiece, driver or fixture interface.

WEBER explains automated feeding as storage, orientation, separation and an air flow adjusted to the part to move it through a hose. It describes ring sensors in the hose and a brake near the driver. DEPRAG’s screw presenter, by contrast, separates a screw and makes it available at a defined pick-up point for magnetic or vacuum pick-up. The RFP must name the required hand-off point before quotations can be compared fairly.

Describe five stages of completion: correct orientation, separation of exactly one screw, arrival at the specified position and time, successful pick-up by the tool or operator, and detection and recovery when a stage fails. Different suppliers can own different stages, but the integrator must document each interface and its acceptance test.

Build a physical screw register before choosing a machine

The first deliverable should be a screw register, not a product shortlist. Collect approved drawings, supplier part numbers, representative production lots, and physical samples near the tolerance extremes. Screws with the same nominal thread can differ in head diameter and height, under-head length, tip, thread, washer, magnetism, oil, coating and burrs. At the pick-up point, head orientation and tip position matter as much as nominal diameter.

The OHTAKE・ROOT KOGYO NJR series lists M2.0–M6.0, an under-head length up to 18 mm and approximately 150 cc capacity; the manufacturer also discusses spring-washer screws. These are published limits for that series, not a guarantee for every head, coating and washer within the diameter range. Use actual production screws in the trial even when the catalogue dimensions appear to match.

Compare the feeding method and the hand-off method separately

Similar product names can hide different outlet conditions. The table compares procurement choices, not the performance ranking of specific models. Shortlist two or three architectures against the actual screws and line layout.

WEBER’s technical guide describes its ZEB bowl as using vibration to move fasteners along a spiral path and its ZEL step feed as a gentler, quieter approach. The ZEL product page lists a low-vibration outlet rail, compatibility with coated and sensitive parts, inlet control, escapement and sensors. DEPRAG positions its presenter as a convenient route for manual and stationary screwdriving and describes exchangeable guide rails. These facts inform a shortlist; they do not replace a trial with the user’s parts.

Avoid blanket claims that all bowls are cheaper or every step feeder is clean. Price depends on separation tooling, controls, sensors and installation. Technical cleanliness depends on the incoming part, abrasion, air, hose, outlet and cleaning regime. Compare candidates with the same screws, count definition and workload.

When to choose a presenter or a hose-fed unit

A presenter deserves early consideration when the operator or fixed spindle is close to the feeder and controlled pick-up is important. DEPRAG states that an output signal can let a higher-level controller monitor the pick-up position. Test the actual magnetic or vacuum tool, non-magnetic screws if used, and whether an uncollected screw remains after an aborted pick-up.

A hose-fed system is relevant when the storage position is distant from the driver. The OHTAKE・ROOT KOGYO BS-P is a pneumatic model. Its published page lists M1.0–M5.0, about 1.2 seconds per screw and a required pre-production sample test. The same page states up to 18 mm shaft length in its introduction but up to 12 mm under-head length in its detailed specifications. If a candidate screw approaches that boundary, obtain the current drawing and written confirmation after sample testing. WEBER also notes that achievable cycle depends on the fastener and feed-hose length. Never copy a fastest catalogue rate into a line guarantee.

Calculate the demand pattern, not just a catalogue cycle time

Required capacity is not defined by product takt alone. Divide product takt by the number of screws only as a first average, then map the actual tightening sequence, simultaneous stations, buffers and changeovers. For example, six screws in a 60-second product cycle imply an average ten-second interval. If all six are needed during the first 15 seconds, that average conceals the burst demand. Give suppliers both the shortest consecutive interval and the hourly average. The numbers in this example illustrate the method; they are not an industry benchmark.

Actual line output is also affected by replenishment, jam clearing, part isolation, changeover, hose replacement, falling air pressure, restart and PLC latency. Ask for continuous running results on defined lots, stop counts, stop duration and good hand-offs, rather than the quickest single ideal cycle. Fix the start and end of each timing measurement: filling to tool pick-up and escapement command to outlet sensor are different metrics.

Set capacity margin using the slow side of the measured distribution, process variation and refill time rather than an unsupported universal percentage. If one unit feeds several drivers, test simultaneous requests and queue rules. WEBER states that a distributor can feed multiple screwdriving systems, but the achievable number depends on cycle time. Validate the specific demand sequence rather than assuming a fixed number of tools per feeder.

Define detection points, states and interlocks

An outlet “screw present” signal alone cannot distinguish missing delivery, double feeding, wrong orientation, a screw stranded in the hose, or failed pick-up. Consider sensing at hopper level, entry, after escapement, along the hose, at the end point and at the tool. The goal is not to add every sensor. For each failure mode, record the detection signal, the stop point and the recovery instruction visible to the operator.

A useful control sequence is idle → feed request → one-screw separation → transport or presentation → pick-up confirmation → tightening enabled → tightening result → next request. On timeout or inconsistent signals, limit retries and stop in a defined safe state. Do not attempt to clear a suspected double feed by injecting another screw. Show where the jam occurred, record what remains in the tool, identify the workpiece and require a checked restart.

WEBER describes PLC processing of sensor OK/NOK signals, including fill level, inlet and actuator position. Its technical guide describes ring sensors in the hose and an outlet brake that restrains a fast-arriving part near the spindle. In an RFP, ask which devices are standard, which are options, and which states are made available to the higher-level PLC.

Specify more than voltage levels in the interface schedule. Define feed request, ready, start, one-screw arrival, fault, reset, manual mode and changeover. For each signal state the sender, receiver, trigger, timeout and power-recovery initial state. For the broader assembly cell and its automation boundary, see our assembly automation and robot planning guide. Here the focus is the screw hand-off.

Put Thai factory conditions into the RFP

“Suitable for Thailand” is not a measurable specification. Record the installation footprint, delivery path, service-door clearance, refill height, hose route to the tool, power supply, compressed-air quality and pressure, grounding, noise, surrounding temperature and humidity, dust or oil, PLC I/O and equipment network. Product models have different limits, so copy no generic value into the RFP without checking the site.

For pneumatic feed, a straight-line distance on a floor plan is insufficient. Draw the vertical movements, collision zones, bend radii, replacement slack, end orientation and cleaning access. Too little air may strand a screw; too much may damage a part or nosepiece on arrival. Set the operating window for the actual part and route and verify it in both the supplier’s FAT and the installed SAT. If the factory has a known range of utility variation, specify and test its boundaries.

Include Thai-language operator indications, aligned Thai/English/Japanese alarm terms where needed, and replacement instructions used by local maintenance staff. The critical part is not translation alone. The operator needs a physical jam-location drawing, rules for residual screws and changeover checkpoints. Identify who replenishes, changes over and maintains the equipment before claiming that the installation will save labor.

Manage mixed screws and traceability outside the feeder

Screws are small and visually similar, so part mixing is a serious failure mode. Emptying a hopper does not prove that the rail, escapement, hose and nosepiece are empty. Changeovers require a physical zero-residual check along with verification of recipe, fixture, driver bit and packaging label. Do not treat equal diameter as permission to use an unapproved part.

For traceable products, connect product serial, screw lot, feeder recipe and tightening result at the granularity required by the customer and risk analysis. One-screw traceability can add significant process and data burden; decide the necessary resolution deliberately. At a minimum, consider recording changeover time, loaded lot, container ID, affected work-in-process range and stop/restart history. Vision classification can be evaluated, but oil, reflection, posture and occlusion must be included in the test; a camera should not be declared a guaranteed substitute for physical segregation or label checks without evidence.

A feeder’s OK signal means the defined hand-off occurred. It does not prove the final joint quality. Torque, angle, seating, lifted heads and thread damage belong to the tightening system and product inspection. Treat feed completion and tightening completion as separate events and determine how a failed workpiece is isolated.

Design a sample trial that makes vendor demos comparable

Do not send only one bag from a nominal good lot. Prepare identified samples near dimensional limits, with coating and oil variation, captive washers, transportation scuffs and storage conditions that actually occur in production. Keep intentional mixed or damaged parts under controlled test conditions and out of production stock. The BS-P product page explicitly calls for a sample check before the build-to-order unit is made.

For each lot, log screw count, correct hand-offs, missing feeds, doubles, inverted parts, snagging, surface damage, ejection, stop time and recovery time. Reconcile counters to physical samples and retain photos of rejected parts and event logs. Define how much cleaning and tuning is allowed before and during the run, and how operator interventions are counted. Otherwise, candidate results are not comparable.

Do not borrow a universal pass threshold from this article. The buyer must set it against product risk, takt and downstream inspection, then give every bidder the same test. For example, require three identified lots in sequence, a log of every stop and isolation of the first part after each changeover. Test length should reflect the failure frequency one needs to detect: a few dozen successful cycles do not rule out rare double feeds or wear during longer running.

What a screw feeder RFP should request

Instead of writing only “M3, 60 screws/minute,” distinguish the required outcome from design freedom. Attach the screw register and equipment layout. Request the proposed method and its rationale, unsupported parts, proven versus newly engineered components, and the assumptions behind consumable life.

Compare installed total cost: machine, spare rails, nosepieces, hoses, filters, sensors, driver and PLC changes, commissioning, Thai training, testing, spares and consumables. A future screw change might require a rail swap or a different architecture. The DEPRAG brochure index separately lists presenters, mini feeders, step feeders and storage devices. Use the actual proposed modules and boundaries rather than a broad category name.

Screw feeding FAT and SAT: prove different risks

A factory acceptance test (FAT) demonstrates the agreed configuration at the maker or integrator. A site acceptance test (SAT) demonstrates the installed process in the Thai factory with utilities, hose, driver, fixture, higher-level PLC and operator procedure. SAT is not a repeat of the identical checklist: assign to it the risks introduced by shipping, installation and the real route. A screw that fed reliably in a short laboratory hose may stop in the installed path.

At FAT, verify approved drawings against the built unit, part and lot IDs, good and rejected counts, blocked sensors, empty hopper, jams, simulated doubles, emergency stop, power recovery, recipe change and logging. Record unsupported shapes as a formal restriction or change request. At SAT, add actual hose bends and length, air variation, driver angle, fixture interference, equipment signals, Thai alarm text, replenishment, cleaning, replacement and recovery by the local maintenance team.

The signed record should include test ID, requirement ID, screw lot, machine/software revision, counting method, start and finish, result, stop history, owner, open items and retest date. “Ran for one hour” cannot tell a later reviewer how many good hand-offs occurred or what was excluded. If joint quality is checked during the same run, put feeder acceptance and tightening acceptance in separate columns.

A pick-up failure can be caused by the fixture or nest position rather than by the feeder. Changing feeder settings alone may simply move the defect. Set a datum and tolerance for the hand-off point; see our jig design and manufacture guide when defining that interface.

Decide on downtime, recovery and maintenance as part of selection

A high-availability installation must be recoverable as well as resistant to jams. Test isolation before a cover is opened, locations where residual screws can collect, inspection inside the nosepiece, cleaning tools and the first screw after a restart. If the maintenance technician must remove a hose, include leak and connection checks after reconnection.

Include preventive cleaning, rail or brush wear, hose damage, sensor-window condition, filters, air preparation and local spare stock in the quote. Actual replacement intervals depend on part material, surface and operating hours; recalibrate them from initial running data. Before contracting, confirm the Thai service contact, working language, parts lead times and remotely accessible logs.

An investment case should measure more than seconds saved from hand motions. Establish the current rates of feed waiting, double feeds, jam recovery, changeovers, surface damage, reinspection, spares and maintenance, then measure after installation using the same definitions. If screw supply is not the line constraint, a faster feeder may not increase shipment capacity. Decide whether a modest presenter improvement or an integrated hose-and-driver solution addresses the actual bottleneck and quality risk.

Build a test matrix for combinations that a simple demo misses

Testing one nominal condition at a time can miss failures caused by interacting conditions. Use a matrix with screw lot, machine setting, operating state and site condition as axes. You need not test every theoretical combination; prioritize combinations that occur in the plant or could release a defective product. For example, an oily lot, the longest approved hose route and restart after a long pause may be more revealing together than separately. If a combination cannot occur in your process, record why it is excluded.

For screws, include a nominal lot, dimension extremes, captive washers, supplier changes and coating changes. For equipment, include normal and boundary air conditions, standard and replaced hose routes, a nearly empty hopper and the first run after a rail change. For operation, include peak bursts, ordinary requests, restart, first part after changeover and recovery after a fault. Identify every applied condition and its trial order.

Do not judge only a single feed success rate. Log good hand-offs, whether faults were detected, whether an incorrect screw reached the tool, whether affected work-in-process was quarantined and whether the first post-recovery screw was correct. A detected double feed still fails if a second screw remains in the nosepiece and the system automatically restarts. Safe stopping, a visible residual location and identification of affected product show containment. Test the sequence of detection, containment and recovery, not just the number of faults.

Version-control the settings used during trials: rail width, vibration, air pressure, sensor threshold, PLC timeout, hose and nosepiece. If settings change after a favorable result, retest affected cases. A run that succeeds only while a supplier engineer is present is not proof that local maintenance can operate it. In the final exercise, have the Thai team replenish, change over, clear a jam and perform pre-start checks using only the agreed procedure and tools. Record time and error-prone steps.

Attach the matrix to the RFP. Ask each bidder which rows it cannot test, why, and whether tooling or fees are required. Label rows for FAT, SAT or initial production monitoring. For unfinished acceptance rows, record temporary operating restrictions, owner, deadline and retest evidence. This separates catalogue fit from acceptance on the installed line.

A practical adoption sequence

Use nine checkpoints: (1) screw register and layout, (2) hand-off boundary, (3) takt and failure modes, (4) candidate methods, (5) sample test, (6) RFP and cost comparison, (7) FAT, (8) SAT, and (9) maintenance hand-over. Include manufacturing, quality, maintenance and procurement in the approvals. State who requests revalidation after a screw drawing revision.

The first supplier discussion does not require a perfect RFP. Physical samples of three to five target parts, product takt, tool and feeder positions, and current stop and reject records are enough to begin architectural screening. Do not promise model fit, cost, delivery date or productivity gain without the physical parts and site conditions. Ask vendors to distinguish “possible candidate” from “demonstrated fit with your screws.”

FAQ: selecting an automatic screw feeder

Can one automatic screw feeder be shared by screws with the same diameter?

Sometimes, but head and under-head dimensions, washer, coating, magnetism and burrs still affect fit. Validate rail and recipe changes and removal of residual parts with actual screws. DEPRAG describes exchangeable guide rails for some presenters; that is not unlimited geometric compatibility.

What should be held constant in a screw feeder comparison?

Use the same screw lots, input condition, hose and tool boundary, count start and end, trial duration, permitted intervention and surface-damage criteria. Fastest published rates are not directly comparable when these conditions differ.

How should the installation cost be estimated?

Compare the installed cost of the feeder, rails, hopper, sensors, hose, driver and PLC changes, installation, FAT/SAT, training, spares and maintenance. Account for planned future parts and changeover time. Site-specific prices require sample and installation review.

Which samples should accompany a screw feeder RFP?

Include approved drawings, representative lots and identified extremes or production-relevant variants in supplier, coating, washer and storage condition. Segregate intentionally defective trial parts from production stock.

Can SAT be omitted after FAT passes?

SAT verifies the actual hose route, air, tool, fixture, PLC and local operator procedures. FAT alone does not prove the installed integration. Agree acceptance and open-item handling for both tests before ordering.

Is there a feeder that guarantees zero jams?

Results depend on geometry, surface, mixed parts, refill and site conditions; a general zero-jam guarantee is not credible. Measure stops, detection and recovery over defined samples and runs, and prevent faulty workpieces moving downstream.

Conclusion: choose with real screws and acceptance evidence

Define hand-off, actual screw variation, burst demand, detection, recovery and site conditions before committing to a presenter, hose, bowl or step architecture. Manufacturer ratings narrow the field; comparable sample tests, clear RFP responsibility and FAT/SAT records make the final decision. In a Thai factory, safe local recovery and residual-screw control during changeover belong in the purchasing requirement.

TOMAS TECH can help structure the screw register, hand-off boundary, sample trial, RFP and FAT/SAT criteria for a Thai assembly line. You can begin with the actual screws and workstation conditions even before selecting an architecture. Contact us.

Primary sources

• WEBER, Feeding systems
• WEBER, How automated feeding works
• WEBER, Step feeder ZEL
• DEPRAG, Screw presenter
• DEPRAG, Feeding Technology brochures
• OHTAKE・ROOT KOGYO, NJR Series
• OHTAKE・ROOT KOGYO, BS-P Series

Product details reflect the cited manufacturer pages at review time. Confirm current specifications and application to your screws through the manufacturer and a sample trial.