HALT Testing Systems

The LEHALTHASS is a highly accelerated life test (HALT) and highly accelerated stress screen (HASS) system. It combines fast temperature cycling with repetitive-shock vibration in one chamber, so design weaknesses in electronic and mechanical assemblies appear in hours of stepped stress instead of long conventional tests.

How it works

The vibration table is a six-degree-of-freedom (6DOF) repetitive-shock table driven by pneumatic hammers. It produces random broadband excitation from 10 Hz to above 5,000 Hz with a consistent power spectral density, exciting many frequencies at once in complex assemblies. The hammer and table design runs without lubrication and without valves, and needs no external cooling. The table is field adjustable to restore its original PSD levels.

The thermal system heats with nichrome wire and cools with liquid nitrogen through vacuum-jacketed (VJ) valves and manifold. Ramp rates are 60 to 100 °C per minute. Proportional valve control meters LN2, which reduces two-phase flow problems seen with on/off solenoid control. VJ lines prevent condensation and dripping. LN2 can come from low-pressure Dewar tanks or higher pressure cylinders and bulk tanks.

Chamber and controls

• Stainless steel interior, painted exterior, two full opening doors
• High-velocity airflow for fast product temperature change
• Two-position table for taller samples and lower LN2 use on small items
• PC and PLC control with programming and datalogging of vibration and thermal profiles
• One accelerometer for table control plus three additional inputs
• Two thermocouples, product and air, plus four additional inputs; eight event relays
• Options: integrated spectrum analyzers and data acquisition

Specify for your project

• Product size and mass, to choose table position
• Temperature limits of the test profile
• LN2 supply: Dewar, cylinder or bulk tank
• Number of accelerometer and thermocouple channels
• Data acquisition needs

This description defines the product family. Guaranteed performance, included hardware, exclusions, interfaces and acceptance criteria are stated only in the project-specific technical proposal and approved datasheet.

The technology has matured from a simple thermal shock chamber with a vibration table to an integrated testing system. The technology provides the extreme stresses necessary to rapidly find design flaws missed by traditional methods.

The table delivers six-degree-of-freedom, random, broadband excitation (10 Hz to above 5,000Hz) with a consistent power spectral density profile that eliminates "picket fencing." The thermal chamber's conditioning system features vacuum-jacketed liquid nitrogen cooling and nichrome wire heating, resulting in ramp rates of 60 to 100˚C per minute.

Features

• Vibration Technology: 6DOF repetitive-shock table
• Simultaneous excitation at multiple frequencies for testing complex assemblies
• Pneumatic hammer/table design is lubrication-free and valvelessQuiet operation without external cooling requirements
• The table is field-adjustable for resetting to original PSD levels, ensuring consistent performance. (Adjustment included in our preventative maintenance agreement.)

Cooling System

• Vacuum Jacketed (VJ) liquid nitrogen (LN2) valves and manifold.
• Proportional control and valve system for maximum LN2 efficiency and consistent temperature control, while reducing two-phase (gas/liquid) states that cause problems in traditional on/off solenoid-based control.
• VJ eliminates condensation, dripping water, OSHA safety concerns, and energy loss compared to other insulation methods.
• Efficient, economical LN2 usage with either low-pressure Dewar tanks or higher pressure Permacyl and bulk tank systems.

Chamber Design

• Stainless steel interior, painted exterior, with two full opening doors
• High-velocity airflow for improved product temperature change rates
• Two-position table for flexibility to test taller samples, improved ergonomics, and less LN2/electricity usage for smaller test items
• Advanced chamber insulation combined with our low-noise hammers results in very quiet operation, even at maximum vibration levels.
• Adjustable feet for leveling unit.

Control System

• PC and PLC-based controls
• Programming, operation, and datalogging for vibration/thermal profiles.
• One accelerometer for table control (three additional inputs available)
• Two thermocouples: one for product, one for air (four additional inputs available)
• Eight event relays for external controls
• Optional integrated spectrum analyzers and data acquisition systems.