Schraubfallanalysen & technische Untersuchungen
Schraubverbindungen nicht schätzen, sondern messen: Wir analysieren reale Schraubfälle, Reibwerte, Vorspannkräfte, Montageparameter und Versagensgrenzen unter reproduzierbaren Prüfbedingungen – für Entwicklung, Qualitätssicherung, Produktion und Schadensanalyse.
Schraubfallanalyse
Originalbauteile prüfen und Drehmoment, Drehwinkel sowie Vorspannkraft erfassen.
Mehr erfahren →Reibwertermittlung
Reibwerte von Schrauben und Muttern sowie Verhalten von Gewindesicherungen untersuchen.
Reibwerte prüfen →Montageparameter
Eindreh-, Überdreh- und Versagensmomente zur sicheren Prozessauslegung bestimmen.
Prozess auslegen →Setz- & Langzeitverhalten
Einfluss von Zeit, Temperatur und Schwingungen auf die Klemmkraft untersuchen.
Langzeitverhalten prüfen →
Information
Information
Joint analysis for secure and reproducible bolted joints
A reliable bolted joint cannot be judged solely on the basis of a theoretically calculated tightening torque. Friction, fasteners, component materials, surfaces, thread locking devices, speed, and settling behavior influence the actual preload force generated in the real joint. With a professional joint analysis, these influences are investigated metrologically, and reliable assembly parameters for the specific application are determined.
What can be investigated in a joint analysis?
| Investigation | Measured variable / Result | Typical benefit |
|---|---|---|
| Friction coefficient determination | Friction coefficients of screws and nuts | Securing the relationship between torque and preload |
| Direct fastening | Drive-in, forming, and overtightening torques | Determining a suitable assembly window |
| Failure analysis | Breakage and overtightening torques | Determining the load limit of the joint |
| Loosening behavior | Loosening and breakaway torques | Evaluation of assembled or secured bolted joints |
| Residual preload | Retightening torque and clamping force | Evaluation of the remaining preload force |
| Settling behavior | Clamping force over time and temperature | Evaluation of relaxation and retardation |
| Speed influence | Behavior at different tightening speeds | Optimization of the assembly process |
The real bolted joint on the test bench
For the investigation, the real bolted joint is set up on a test bench as true to the original as possible. The components and fasteners are tightened with a programmable EC tightening spindle.
Measure during fastening
Torque, angle, and clamping or preload forces are measured during the fastening process.
Evaluate data afterwards
The recorded measurement data can be evaluated graphically and in tabular form. The results are then documented in an investigation report.
Friction coefficient determination on screws and nuts
A significant part of the torque applied during tightening is consumed by friction in the thread and under the head or nut bearing surface. Changes in coating, lubrication, surface, or fastener can therefore affect the preload actually achieved.
With a friction test, the friction conditions of a specific screw-nut combination can be experimentally investigated. VMA offers the determination of friction coefficients on screws and nuts according to DIN EN ISO 16047.
Investigating thread locking devices and friction torques
Clamping or adhesive thread locking devices change the friction torque occurring during fastening. For process design, it can therefore be crucial to determine how much torque is already generated by the locking device and what proportion is actually available for generating the preload.
Friction torques for adhesive or clamping thread locking devices can be investigated, among others, according to DIN EN ISO 2320 and DIN 267 Part 27/28.
Experimentally determine optimal assembly parameters
Especially with direct fastenings in plastic, light metal, or steel, the tightening torque must reliably lie between the necessary drive-in torque and the failure limit of the joint.
By measuring drive-in, forming, overtightening, and failure torques, a suitable process window for assembly can be determined. The test data can be statistically evaluated to secure process planning.
Settling behavior, temperature, and long-term clamping force
A bolted joint may have sufficient preload immediately after assembly and still partially lose it during operation. Causes can be, for example, settling processes, temperature changes, vibrations, or time-dependent material effects.
In long-term and temperature tests, it can be investigated how these influences affect the clamping force of the joint. This allows relaxation and retardation effects to be evaluated metrologically.
How a joint analysis works
When is a joint analysis useful?
hyTool & VMA engineering – Tools and engineering from one group
The technical investigations are carried out by VMA engineering GmbH. VMA engineering is a 100% sister company of hyTool. This allows us to combine our experience with professional bolting technology and industrial tools with test bench technology, measurement technology, and engineering expertise.
Describe the bolted joint and the technical problem to us. Based on your application, a suitable analysis and test plan can be determined. If necessary, the application can also be examined on-site.
Frequently asked questions about joint analyses
What is a joint analysis?
A joint analysis involves the metrological investigation of a specific bolted joint under defined conditions. This can include recording and subsequently evaluating torque, angle, and clamping or preload force.
What data is measured during a joint analysis?
Depending on the investigation objective, torque, angle, and clamping or preload forces can be recorded. Further statements about the behavior of the bolted joint can be derived from this measurement data.
Can the friction coefficient of a screw be determined?
Yes. VMA engineering offers the determination of friction coefficients on screws and nuts according to DIN EN ISO 16047. This is relevant, for example, for evaluating coatings, lubricants, or different fasteners.
Can thread locking devices be investigated?
Yes. Friction torques of adhesive or clamping thread locking devices can be investigated. This allows an assessment of the influence of the locking device on the fastening process.
How is the correct tightening torque determined experimentally?
Depending on the bolted joint, drive-in, forming, tightening, overtightening, and failure torques can be measured. From the measured values, a suitable assembly window for the specific joint can be derived.
Can the preload force be measured directly?
Yes. With a suitable test configuration, the clamping or preload force can be recorded during the fastening process and evaluated together with torque and angle.
Can it be investigated why a bolted joint loses preload?
Long-term and temperature tests allow investigations of settling behavior. This can include considering the influences of time, temperature, and vibrations on the clamping force.
Do I receive a report after the analysis?
Yes. The recorded measurement data is evaluated and can be presented graphically and in tabular form. The result of the investigation is then documented in an investigation report.
Who performs the joint analyses for hyTool?
The technical execution is carried out by VMA engineering GmbH. VMA engineering is a 100% sister company of hyTool and complements our offer with test bench technology, measurement technology, and technical joint analyses.