HMI Design Pattern for Roll Forming Machine Operators — Fast, Safe, and No Confusion

Introduction — Why HMI Design Matters in Roll Forming Machines

The Human Machine Interface (HMI) is the primary way operators interact with a roll forming machine. Even if the PLC logic is well designed, a poorly designed HMI can cause serious operational problems.

Common problems caused by bad HMI design include:

• operators pressing the wrong buttons
• confusion about machine status
• slow troubleshooting during faults
• incorrect recipe selection
• unsafe machine operation.

A well-designed HMI allows operators to understand machine status instantly and perform tasks quickly without confusion.

For roll forming machines, HMI design should focus on three key principles:

• speed of use
• operator safety
• clarity of information.

This article explains the design pattern used by many professional automation engineers when building operator interfaces for roll forming machines.

Understanding the Operator’s Environment

Before designing an HMI, it is important to understand the operator’s working conditions.

Roll forming machine operators typically work in environments that include:

• loud industrial noise
• bright lighting or outdoor conditions
• oil contamination
• gloves or protective equipment.

These conditions influence how information should be displayed.

Interfaces must be simple, readable, and easy to operate under industrial conditions.

Principle 1 — Keep the Main Screen Simple

The main machine screen should display only the most important information.

Operators should be able to answer three questions immediately:

• Is the machine running?
• If not, why?
• What should I do next?

Too much information on the main screen creates confusion.

Typical elements on a main screen include:

• machine status indicator
• start and stop controls
• current product information
• basic production counters
• alarm status.

Complex technical information should be placed on separate screens.

Clear Machine Status Indicators

Machine status should always be visible.

Typical status indicators include:

Running

Machine producing normally.

Ready

Machine ready to start but not currently running.

Stopped

Machine stopped by operator.

Fault

Machine stopped due to an alarm.

These states should be clearly displayed with color coding.

Standard Industrial Color Conventions

Industrial HMIs commonly use standard colors for machine states.

Example conventions:

Green — running
Yellow — warning or setup mode
Red — fault condition
Gray — inactive or disabled function.

Consistent color usage helps operators interpret machine status quickly.

Start and Stop Controls

Machine start and stop controls should be easily accessible.

Design recommendations include:

• large buttons
• clear labeling
• confirmation prompts where necessary.

Critical controls such as emergency stop should remain physical hardware buttons rather than HMI controls.

Principle 2 — Provide Clear Alarm Information

When a fault occurs, operators must understand the cause immediately.

The HMI should display:

• alarm description
• time of occurrence
• suggested corrective action.

Avoid vague alarm messages such as:

System error.

Instead, use clear descriptions such as:

Shear failed to return to home position.

Clear alarm descriptions reduce downtime and improve troubleshooting.

Alarm History Screen

The HMI should include an alarm history screen.

This screen records past alarms with timestamps.

Typical information displayed includes:

• alarm message
• activation time
• acknowledgement time
• reset time.

This information helps technicians diagnose recurring issues.

Principle 3 — Organize Screens by Machine Function

Complex machines require multiple HMI screens.

Screens should be grouped logically by subsystem.

Typical screen categories include:

• machine overview
• production data
• recipe management
• alarm history
• maintenance diagnostics.

This organization makes navigation easier for operators.

Production Information Screen

Operators need access to production statistics.

Typical data displayed includes:

• panel count
• batch count
• production rate
• scrap count.

Clear production data helps operators monitor machine performance.

Recipe Selection Screen

Many roll forming machines produce multiple products.

The HMI should allow operators to select product recipes easily.

Typical recipe screens include:

• product list
• recipe preview
• load confirmation.

Operators should not be able to modify recipes unless authorized.

Preventing Operator Errors

One of the most important goals of HMI design is preventing mistakes.

Methods include:

• confirmation prompts for critical actions
• user access levels
• clear warning messages.

For example, changing recipes during production may require operator confirmation.

User Access Levels

Different users may require different levels of access.

Typical access levels include:

Operator

Can start and stop machine, select recipes, and view alarms.

Supervisor

Can modify production settings.

Engineer

Can access advanced diagnostics and configuration.

Access control prevents unauthorized changes.

Maintenance and Diagnostics Screens

Maintenance technicians require access to machine diagnostics.

These screens may display:

• sensor status
• drive information
• servo positions
• hydraulic pressure readings.

Operators usually do not need to access these screens.

Visual Representation of Machine Status

Graphical representations help operators understand machine conditions quickly.

Examples include:

• animated machine diagrams
• moving indicators showing strip flow
• color-coded sensor states.

These visual elements make the interface more intuitive.

Avoiding Information Overload

Too much information can make an HMI difficult to use.

Design guidelines include:

• limit information per screen
• group related data
• avoid unnecessary graphics.

Simple interfaces are usually more effective.

Fast Navigation

Operators should reach important screens within one or two touches.

Typical navigation structure:

Main Screen
→ Alarm Screen
→ Recipe Screen
→ Production Screen.

Deep navigation hierarchies should be avoided.

Screen Layout Consistency

Consistency improves usability.

Every screen should use similar layout elements such as:

• navigation buttons in the same location
• consistent color usage
• standard fonts and text sizes.

Operators learn the interface more quickly when layouts remain consistent.

Touchscreen Design Considerations

Industrial HMIs often use touchscreens.

Buttons must be large enough for gloved hands.

Typical recommendations include:

• large touch targets
• spacing between buttons
• clear visual feedback when pressed.

This improves usability in industrial environments.

Data Logging and Reporting

Modern HMIs often collect production data.

Typical logs include:

• panel counts
• downtime events
• machine alarms.

These logs help managers analyze machine performance.

Commissioning HMI Systems

During machine commissioning, engineers should test all HMI functions.

Typical checks include:

1 verifying navigation between screens
2 testing alarm displays
3 confirming recipe selection functions
4 checking user access levels.

Testing ensures the interface works as expected.

Preventative HMI Maintenance

HMI systems should be maintained regularly.

Recommended practices include:

• updating software when required
• backing up HMI configuration
• checking touchscreen calibration.

Regular maintenance ensures reliable operator interaction.

Benefits of Proper HMI Design

A well-designed HMI provides several advantages.

These include:

• faster operator training
• fewer operational mistakes
• quicker fault diagnosis
• improved machine productivity.

For roll forming machines operating continuously in industrial environments, effective HMI design is essential.

FAQ — HMI Design for Roll Forming Machines

What is an HMI in a roll forming machine?

An HMI is a touchscreen interface that allows operators to monitor and control the machine.

Why must HMI screens be simple?

Simple screens reduce operator confusion and allow faster decision making during production.

What information should be on the main screen?

Machine status, start/stop controls, alarm status, and basic production information.

Why are color conventions important?

Standard colors help operators recognize machine conditions quickly.

Who should be allowed to modify machine recipes?

Typically supervisors or engineers with appropriate access permissions.

How can HMI design improve machine safety?

Clear alarms, confirmation prompts, and restricted access help prevent unsafe machine operation.