Pancake Load Cells
Low-profile radial strain gauge sensors for press monitoring, calibration transfer, and structural proof testing. DBSL (industrial, 2–200t) and HAPL (reference, 5–50t) series with ±0.01% repeatability.
Quick Reference
- DBSL Series: 2–200t capacity, industrial-grade, ±0.03% nonlinearity, nickel-plated alloy steel, 2–4 day lead time
- HAPL Series: 5–50t capacity, reference-grade, ±0.02% nonlinearity, stainless/tool steel, ±0.002%/°C stability
- Low-profile design: Radial strain gauge configuration, moment rejection, disk geometry optimized for direct load introduction
- Wiring: 4-wire standard (6-wire with sense on HAPL for extended cable runs)
- Loading: M16×1.5 centerline thread (DBSL); load buttons and tension plates available from 1–30t
- Excitation: 5V or 10V DC; mV/V Wheatstone bridge output
- Accessories: Load buttons (1–5t, 10–20t, 30t), tension plates (1–5t)
At-a-Glance Specifications
What Are Pancake Load Cells?
Pancake load cells are ultra-low-profile, disk-shaped force sensors designed for applications requiring minimal vertical space and direct load coupling. Unlike canister load cells (which measure column loads vertically) or button load cells (which use point contacts), pancake designs use a flat loading surface perpendicular to a radial strain gauge bridge, allowing them to reject off-axis moments and measure true axial force under conditions where lateral forces or tilting loads might skew results.
Transcell offers two series: the DBSL (industrial) for production and field measurement, and the HAPL (reference) for calibration transfer and precision laboratory work. Both use 4-wire mV/V Wheatstone bridge transducers with nickel-plated or stainless steel construction.
How Pancake Load Cells Work
Radial Strain Gauge Configuration
Pancake cells employ a radial strain gauge arrangement where the sensing element is positioned to respond to diametral stress changes. When an axial load is applied to the flat top surface, the disk body deflects slightly, creating radial strain that the gauges detect. This geometry offers several engineering advantages:
Moment Rejection
Radial configuration naturally rejects off-axis tilting moments, ensuring accurate force measurement even under slightly eccentric loads typical in real-world press applications.
Low Profile
Disk shape allows direct load introduction with minimal vertical height, critical for confined spaces in presses, test fixtures, and production automation.
Direct Coupling
Flat, hard-faced loading surface threads directly into a mating structure, eliminating intermediate adapters and reducing error sources.
Wheatstone Bridge and Output
Both DBSL and HAPL series use a 4-wire full Wheatstone bridge configuration connected to standard 5V or 10V excitation. The bridge output is in millivolts per volt (mV/V), typically 2.0–3.0 mV/V at rated load, making integration with industrial amplifiers, data loggers, and PLC analog inputs straightforward.
DBSL vs. HAPL Series
Transcell offers two distinct product lines optimized for different operational contexts:
| Specification | DBSL (Industrial) | HAPL (Reference) |
|---|---|---|
| Capacity Range | 2–30t standard (ext. 200t) | 5–50t |
| Rated Output | 3.0 mV/V ±0.25% | 2.0 mV/V |
| Nonlinearity | ±0.03% | ±0.02% |
| Hysteresis | ±0.05% | ±0.03% |
| Repeatability | ±0.01% | ±0.01% |
| Safe Overload | 150% | 150% |
| Construction Material | Nickel-plated alloy steel | Stainless steel or tool steel |
| Temperature Coefficient | ±0.015%/°C | ±0.002%/°C |
| Wiring | 4-wire standard | 4-wire standard, 6-wire with sense available |
| Cable Length | Standard lengths available | 5m standard; custom on request |
| Lead Time | 2–4 days from stock | 5–7 days |
When to Choose DBSL
Select DBSL for production line monitoring, field installation, and applications where rapid lead time and broad capacity range (up to 200t extended) outweigh the need for ultra-high stability. Industrial-grade nonlinearity (±0.03%) and 0.05% hysteresis are well within tolerance for most press, testing machine, and automation workflows.
When to Choose HAPL
HAPL is designed for calibration transfer standards, laboratory measurement, and reference installations where temperature stability (±0.002%/°C) and exceptional repeatability support long-term traceability. The optional 6-wire configuration with remote sense is valuable for extended cable runs where lead resistance would otherwise degrade accuracy.
Key Features & Technical Attributes
Construction & Durability
DBSL pancake cells feature nickel-plated alloy steel construction, offering good corrosion resistance for shop-floor environments. HAPL series employ stainless steel or tool steel for applications requiring chemical resistance or cleanroom compatibility. Both series have flat, hard-faced loading surfaces designed to withstand repeated contact with hardened steel adapters and load buttons without deformation.
Load Introduction & Mounting
Centerline Loading: DBSL uses an M16×1.5 centerline thread for direct load introduction. The mating surface should be flat to within 0.002 in. total indicated runout (TIR) to ensure distributed contact and minimize measurement error from eccentric loading.
Load Buttons & Adapters: Transcell supplies load buttons in 1–5t, 10–20t, and 30t ranges, as well as tension plates for 1–5t capacities. These hardened steel accessories couple the load cell to the test structure and distribute force evenly across the sensing surface.
Torque Specification: Standard torque on the M16×1.5 thread is approximately 40–60 N⋅m for DBSL. Under-torquing allows movement and hysteresis; over-torquing can preload the load cell. Consult the product datasheet for exact values.
Wiring & Signal Integrity
Standard 4-wire configuration: Red (Excitation+), Black (Excitation−), Green (Signal+), White (Signal−), Bare (Shield). The shield should be connected to system ground at one point only to prevent ground loops.
HAPL’s optional 6-wire sense lead allows the amplifier to measure excitation voltage directly at the load cell terminal, compensating for voltage drop in extended cable runs and preserving output accuracy over distances up to 100+ meters.
Who These Load Cells Are For
Pancake load cells serve distinct buyer personas with different technical priorities:
Manufacturing Engineers (Hydraulic & Mechanical Press Operators)
Monitor actual load during press cycles to verify machine calibration, detect worn tooling, and ensure product consistency. DBSL’s 2–4 day lead time and industrial-grade accuracy make it the standard choice for retrofit monitoring in existing production lines.
Quality & Materials Testing Labs
Use pancake cells in tensile frames, compression testers, and multi-axis test fixtures. HAPL reference-grade units provide traceable measurement for compliance testing, material certification, and third-party validation.
Aerospace & Defense Supply Chain
Pancake cells are standard in structural proof testing, fastener preload verification, and spot welding force monitoring. Reference-grade HAPL cells support documented force traceability required by AS9100 and equivalent certifications.
Calibration Service Providers
HAPL cells serve as transfer standards, bridging between reference weights and in-service load cells. Superior temperature stability and repeatability ensure that calibration curves remain valid across seasonal temperature swings and production batch variations.
Selecting the Right Capacity
Pancake load cell capacity must be selected based on the maximum expected load plus a safety margin. The rule of thumb is to size for 1.5–2× the maximum operating load. This practice serves multiple purposes:
- Resolution: A load cell operates with best resolution in the upper 70–80% of its range. Operating at 50% of capacity provides a 1.3× safety buffer while maintaining excellent sensitivity.
- Safety margin: Protects against occasional overload conditions (tool slippage, unexpected part weight variance) without reaching the 150% safe overload limit.
- Stability: Load cells exhibit slightly better hysteresis and repeatability in the mid-to-upper portions of their operating range.
Example Calculation
Suppose a hydraulic press is designed for 10 metric tons maximum. Select a 15t or 20t pancake cell (1.5–2× factor). A 10t cell would operate at 100% capacity at maximum design load, leaving no margin for transient overloads or dynamic spike during press closure.
Mounting and Load Introduction Best Practices
Surface Preparation
The mating surface (top of the load cell) and the interface on the press or test frame must be flat and clean. Use a straightedge to verify flatness to within 0.002 in. TIR. Remove oil, debris, and oxidation with a lint-free cloth and light solvent. A slight amount of anti-seize compound (e.g., PTFE-based) on the M16×1.5 thread helps prevent galling on stainless steel HAPL cells.
Load Button Selection
Transcell supplies hardened steel load buttons in discrete capacity steps (1–5t, 10–20t, 30t). Choose a button rated for the maximum expected load. The button distributes force across the load cell face and reduces point-contact wear that could degrade long-term accuracy.
Torque Application
Use a calibrated torque wrench set to specification (typically 40–60 N⋅m for DBSL M16×1.5). Apply torque in a steady, controlled manner; avoid shock loading. If the load cell is preloaded during installation (e.g., by tightening while the press is closed), subtract that preload from the measurement after the load is removed to obtain true load.
Pancake vs. Other Load Cell Types
Understanding when pancake designs offer advantages over alternatives is critical for system selection:
| Feature | Pancake | Canister (Column) | Button (Point Contact) |
|---|---|---|---|
| Height | Very low (30–50mm typical) | Tall (150–400mm typical) | Low (20–35mm typical) |
| Load Face Area | Large distributed surface | Medium column face | Small point contact |
| Moment Rejection | Excellent (radial design) | Moderate (depends on mounting) | Poor (point contact amplifies tilt error) |
| Cost | Mid-range | Low (simple design) | Low (minimal material) |
| Typical Applications | Presses, bearing preload, materials testing | Tank weighing, hopper discharge, structural load | Force verification, compression only |
Pancake Advantages
Confined Spaces: The low-profile disk shape fits in applications where height is severely restricted, such as beneath die plates in deep-draw presses or inside compact test fixtures.
Moment Tolerance: Unlike button cells, pancakes tolerate slight eccentric loading without significant output drift. This is particularly valuable in field retrofit scenarios where perfect alignment may be impractical.
Distributed Loading: The large, flat sensing surface distributes force evenly, reducing localized stress concentrations and extending sensor life in high-cycle applications.
Standards and Calibration
Transcell’s pancake load cells conform to key industrial standards:
- NIST Traceability: Reference-grade HAPL cells are calibrated against NIST-traceable deadweight standards and supplied with calibration certificates documenting nonlinearity, hysteresis, and temperature compensation.
- ASTM E74 Compliance: Measurement uncertainty for HAPL meets requirements for secondary reference standards used in calibration transfer workflows.
- ISO 6954 (Strain Gauge Load Cells): Both DBSL and HAPL meet applicable performance classes for strain gauge instrumentation.
Calibration Intervals
Pancake load cells should be recalibrated at intervals determined by application severity, environmental exposure, and regulatory requirements. Typical intervals range from 1–3 years for production use, or per customer specification for aerospace and automotive applications.
How Transcell Compares
Transcell’s pancake load cell platform differentiates through:
Extended Capacity Range
DBSL standard line covers 2–30t; extended engineering to 200t. Few competitors offer continuous coverage across this spectrum from a single design family.
Fast Lead Time
DBSL stock inventory supports 2–4 day delivery, critical for production troubleshooting and field retrofits. HAPL reference cells are made-to-order at 5–7 days.
Integrated Accessories
Load buttons, tension plates, and custom adapters are stocked and supported in parallel. One-stop sourcing reduces parts fragmentation and qualification burden.
Temperature Stability
HAPL’s ±0.002%/°C temperature coefficient is among the industry’s best, reducing the need for environmental controls in outdoor or shop-floor testing.
Transcell’s engineering team provides application consulting at no charge, helping customers select the right series, capacity, and accessory configuration before purchase.
Related Products & Solutions
Frequently Asked Questions
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DBSL is an industrial-grade series optimized for production environments, with 2–30t capacity (extended to 200t), ±0.03% nonlinearity, and 2–4 day lead time. HAPL is a reference-grade series designed for calibration work and precision laboratory use, with 5–50t capacity, ±0.02% nonlinearity, superior temperature stability (±0.002%/°C), and 5–7 day lead time. Choose DBSL for speed and broad capacity range; choose HAPL for traceability and long-term stability.
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Pancake cells use a radial strain gauge configuration that responds to diametral stress changes created by axial load. This geometry naturally rejects small off-axis moments (typically ±2–3° tilt) without significant error. However, large eccentric loads or sustained side loads can degrade accuracy. Always ensure the loading surface is clean and flat, and use load buttons or adapters to distribute force evenly.
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Size the load cell for 1.5–2× your maximum expected operating load. This ensures good resolution (the cell operates in the 50–70% range under peak load), provides safety margin for transient overloads, and optimizes repeatability. For example, if your press is rated to 10 tons, select a 15t or 20t pancake cell.
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Yes. HAPL reference-grade cells are commonly used in aerospace structural proof testing and fastener preload verification. They provide the measurement traceability and documentation required by AS9100 and equivalent certifications. DBSL cells can also be used for production monitoring if supported by appropriate calibration documentation. Consult Transcell’s engineering team for application-specific guidance.
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Yes. For standard 4-wire cells, cable length should remain under 30 meters for best accuracy. For longer runs, HAPL’s 6-wire sense configuration compensates for lead resistance and supports cable lengths up to 100+ meters. Custom cable lengths are available. Contact Transcell sales for specific requirements.
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Buffalo Grove, IL 60089, USA