3 Tiers to Customization

In materials testing, accuracy does not begin at specimen failure — it starts within the mechanical pathway responsible for transferring force through the testing system. This pathway, commonly referred to as the load train, governs how force moves from the test frame into the specimen during mechanical testing.

The load train includes every component that carries force, including adapters, grips, fixtures, load cells, and the frame itself. When properly configured, it ensures force is applied in a controlled, axial manner so materials respond according to their true mechanical properties. Even minor inconsistencies within the load train can introduce measurable testing error and compromise force measurement reliability.

As testing requirements become increasingly application-specific, laboratories are often faced with challenges that extend beyond standard testing equipment configurations. Applying the appropriate level of engineering to the portion of the load train where it matters most helps preserve alignment, maintain force integrity, and support repeatable experimentation across tensile, compression, and shear testing environments.

At Universal Test Machine Co., customization is approached as a structured progression across the load train — beginning at the interface (connections and adapters), advancing through the gripping apparatus (grips and fixtures), and extending to the testing system itself.

The Adapter Level

Precision Starts at the Machine-to-Grip Interface

In any materials testing system, the adapter(s) serves as the mechanical bridge between the test frame and the gripping apparatus. While often overlooked, this connection plays a critical role in maintaining alignment throughout the load train and ensuring force is transmitted accurately to the specimen.

Improper interfacing can introduce bending stresses, uneven loading, or thread deformation — all of which can compromise data integrity long before the specimen reaches failure.

For this reason, selecting the proper adapter is not simply a matter of fitment, but one of mechanical precision and load-path stability.

Universal Test Machine Co. supports a wide range of adapter configurations designed to integrate seamlessly with modern materials testing systems across manufacturers and capacity ranges. These include male and female terminations, hybrid combinations, clevis-style interfaces, and fully customized geometries engineered to match the exact requirements of the test setup.

Thread compatibility is another critical consideration within the load train. Adapters are available with clearly defined screw callouts supporting coarse and fine thread profiles, metric and unified standards, application-specific pitch requirements, and high-strength threaded engagements for demanding load conditions.

By properly matching thread form and engagement length to the expected forces, laboratories can prevent premature wear, thread galling, and misalignment — all of which contribute to long-term testing accuracy.

In many cases, a thoughtfully engineered adapter provides the fastest and most cost-effective path to achieving compatibility between existing test frames and new testing requirements, eliminating the need for more extensive system modifications.

Customizations can range from pairing standard vise grips with the correct adapters to hybrid solutions where the grip itself functions as the structural interface. The pinch grip shown is one example of this approach.

Customization at the adapter level allows laboratories to solve interface challenges while preserving the integrity, alignment, and performance of the overall testing system.

The Grip Level

Engineering the Apparatus Around the Specimen

As testing applications become more specialized, customization often advances beyond simple machine compatibility and into the gripping apparatus itself. At this stage, the apparatus is no longer selected solely based on capacity — it becomes fundamentally specimen-dependent.

Material composition, geometry, surface characteristics, elongation behavior, and anticipated failure mode all dictate how force should be introduced into the sample. A properly engineered gripping apparatus ensures the test method is supported rather than influenced by the mechanics of the grip.

One of the most critical — and frequently underestimated — factors in apparatus selection is jaw face geometry.

Here we have three interfaces available on our 1 kN Roller Grips: rubber, serrated, and smooth, similar to jaw selections on vise grips.

The gripping surface serves as the primary mechanical interface between the testing system and the specimen, directly influencing how load is transferred into the material. Tooth profile, serration depth, pitch, and surface pattern all contribute to the balance between holding force and specimen protection.

Rather than relying purely on friction, properly designed jaw faces create mechanical interlock, allowing the apparatus to securely engage the specimen while minimizing the risk of slippage during tensile testing.

However, more aggressive serrations are not always better.

Overly coarse jaw faces can introduce stress concentrations or damage sensitive materials before the true failure point is reached, while insufficient engagement may allow the specimen to slip — producing artificially low strength values and inconsistent mechanical test results.

Optimizing jaw face geometry ensures the specimen fails according to its material properties, not because of the gripping interface.

Another essential variable in grip selection is the maximum expected failure load of the specimen. Understanding this threshold allows engineers to select an apparatus capable of generating adequate normal force without applying excessive compressive stresses that could distort soft polymers, thin metals, or composite samples.

When gripping solutions are improperly matched to the application, the warning signs often appear quickly within the data:

• Specimen slippage prior to break
• Failures occurring inside the grip
• Induced stress concentrations
• Deformation of compliant materials
• Reduced repeatability between tests

In many cases, the testing machine is functioning exactly as designed — the limitation lies within the gripping interface.

Transitioning to a dedicated apparatus allows laboratories to maintain alignment with standardized experimentation while adapting to real-world specimen behavior. Whether accommodating non-standard geometries, supporting higher loads, or protecting delicate materials, grip-level customization plays a defining role in experimental reliability.

The objective is not simply to hold the specimen — it is to create a controlled mechanical environment in which the material can fail naturally and the resulting data can be trusted.

While many testing challenges can be resolved at the apparatus level, increasingly complex applications may demand solutions that extend beyond the grip and into the architecture of the testing system itself.

The Machine Level

System-Level Engineering for Advanced Testing Environments

As testing requirements grow more complex, customization can extend beyond the gripping apparatus and into the architecture of the testing system itself. At this stage, the machine is no longer viewed simply as a force generator — it becomes part of a fully engineered mechanical testing platform designed around the application.

System-level customization often begins with frame modularity. A properly selected test frame must accommodate not only the expected forces, but also the physical envelope required for fixtures, extensometry, environmental chambers, and future testing adaptations. Modular architectures allow laboratories to scale their capabilities without replacing core infrastructure.

If the system is dynamically loaded, the method of actuation becomes equally important, as it directly influences control, precision, and repeatability. Electromechanical systems offer exceptional positioning accuracy and are often preferred for controlled-rate testing, while servo-hydraulic platforms support high-force and dynamic applications.

Selecting the appropriate actuation strategy ensures the equipment complements — rather than constrains — the test method.

At the system level, one of the most critical engineering decisions remains load capacity. A widely accepted guideline is to select equipment with a capacity approximately 1.2 to 2 times the expected specimen break load, providing sufficient overhead while preserving measurement resolution.

Beyond performance considerations, modern laboratories must also account for user safety. Higher-force systems introduce greater stored energy, making protective guarding, controlled failure zones, and operator awareness essential components of responsible laboratory design.

Throughput is another growing priority in advanced testing environments. The number of specimens processed per shift can influence everything from frame selection to software architecture. Increasingly, laboratories are adopting robotic loading and automated workflows to reduce operator fatigue, improve consistency, and support higher-volume testing without sacrificing precision.

System-level customization ultimately enables laboratories to align their testing infrastructure with both current requirements and future innovation. Whether expanding capacity, integrating automation, or configuring machines to support highly specialized fixtures, engineering the system holistically ensures the testing environment evolves alongside the materials it evaluates.

At this tier, customization is no longer about individual components — it is about designing a testing ecosystem capable of delivering accurate, repeatable, and defensible results.