Implementing HALT and HASS in Automotive Design and Manufacturing: A Step-by-Step Guide

Tuesday, October 29 2024

HALT (Highly Accelerated Life Testing) and HASS (Highly Accelerated Stress Screening) are critical testing methods in the automotive industry. They subject components and subassemblies to extreme stresses, uncovering vulnerabilities and design weaknesses. By integrating these processes into your automotive design and manufacturing workflow, you will maximize the reliability of your products, reducing warranty costs and increasing safety. 

This guide will walk you through how to effectively implement HALT and HASS into the design and manufacturing process of your vehicle components and subassemblies. 

 

What Are HALT and HASS? 

HALT and HASS involve subjecting automotive components to extreme stresses to identify design or process weaknesses.  These tests are essential to maximize the reliability of a vehicle’s subassemblies or components. 

While both HALT and HASS are valuable tools, they serve different purposes. HALT is intended to expose hidden design flaws by subjecting components and systems to extreme temperature and vibration stresses as early as possible in the design process. This testing is invaluable for identifying potential issues that might not appear under normal operating conditions or through typical environmental testing. 

On the other hand, HASS focuses on screening components and subassemblies to identify manufacturing-induced defects. It uses the same types of stresses as in HALT but at reduced levels.The key difference between these two testing methodologies is that HALT is used during the design phase of a component or subassembly, while HASS is a screen used in production on 100% of the products manufactured. Together, they form a comprehensive approach to maximizing the reliability of critical subassemblies in a vehicle. 

Below are the steps required to implement HALT and HASS testing for your automotive products. Begin with HALT during the design phase, and implement HASS in the production phase: 

 

Step 1: Define Objectives 

Before implementing HALT and HASS, it’s crucial to define your objectives. These might include improving product reliability, reducing warranty costs, or reducing field failures. Discuss these goals with your team to ensure everyone is aligned on what success looks like. Knowing your objectives upfront will guide the entire testing process. 

 

Step 2: Identify Critical Components and Systems 

Identify the components and subassemblies within your vehicle that are most likely to fail or cause significant issues. Prioritizing these for HALT testing will maximize the value added by HALT. By focusing on critical parts, you ensure that your vehicle’s most vulnerable elements receive the attention they need. 

 

Step 3: Develop a HALT Plan and Prepare for Testing

Developing a HALT plan can be optimized and streamlined by partnering with our expert Solutions Group team. This should be done in collaboration with your product design team. Your plan should include: 

• Test Structure:Identify the stresses and sequence of stresses that will be used in HALT.
• Product Configuration: HALT testing can be done at board-level, lower-level assembly, or upper-level assembly. The product configuration should be defined based on the effects it has on both testability and stress effectiveness.
• Functional Test: A critical component of HALT is that the product is functionally tested during the application of stresses. This requires comprehensive functional test capabilities that can be executed while the product is inside the chamber. 
• Fixturing: Design and implement appropriate fixturing to maximize shock transmission into your product as well as ensure the best application of thermal stresses. 

 

Step 4: Conduct HALT Testing 

Using your HALT plan, execute the testing. It will be important to have design engineers involved in the testing to evaluate and respond to failure modes as they are found. The actual HALT test procedure must be flexible and able to respond to the product’s failure mechanisms as necessary. The ESPEC Solutions Group can provide guidelines to execute the test process effectively. 

 

Step 5: Develop and Implement a HASS Plan 

While HALT focuses on precipitating failures in design, HASS exposes weaknesses introduced during manufacturing. A HASS plan is based on the results from HALT, so completing HALT testing is critical to the success of HASS. 

The implementation of HASS has several considerations that must be incorporated, they include: developing HASS screen stress levels, proof of screen to validate those stress levels, fixture design and validation, and a final fixture integration process. As in HALT, functional tests must be implemented during the screen, so designing the functional test equipment and procedure must be done. ESPEC’s expert team can provide project guidance and services to help you implement any or all of these steps. 

 

Step 6: Analyze and Improve 

HALT and HASS will identify product weaknesses. Investigating and eliminating these weaknesses is an important component to the continuous improvement of the product design. These failure modes can identify changes that will improve reliability and reduce field issues. 

 

Making the Most of HALT/HASS Testing 

Conducting HALT and HASS are critical tools for maximizing reliability and reducing warranty costs for components and subassemblies used in the automotive industry. Implementing these test methods will result in products that routinely exceed customer’s expectations, improving your brand recognition, value, and loyalty.  

If you’re in need of a HALT/HASS testing partner, we’re here to help. At ESPEC, we offer comprehensive testing services and equipment. Connect with a local sales representative today to start a conversation about how our rigorous testing methodologies can improve the reliability of the automotive products you provide.