Different Types of Sheet Metal Hemming
Did you know that sheet metal hemming has existed for thousands of years? Even now, the technique is valuable for original equipment manufacturers (OEMs), sheet metal fabricators, roofing companies, and many more.
When sheet metal edges are folded in hemming, they have higher structural integrity, are more visually appealing, and are safer to use due to smoother edges.
New materials and advancements mean that the nature and applications of metal hemming are constantly changing. The entry of CNC machinery in metal fabrication is a big game changer on which you must capitalize.
Therefore, ProleanTech reiterates the relevance of CNC machining for the edge-manipulating technique. This sheet metalworking technique is a core operation at the company and serves countless clientele globally.
Indeed, we have carved a name as the go-to company for customizable, cost-effective, and high-quality precision sheet metal hemmed parts. We have the coveted ISO 9001:2015 certification as a sign of our flawless performance.
This article details the sheet metal hemming method and introduces our services. Continue reading this handy guide to discover a lasting solution for your metal hemming requirements.
What Is Sheet Metal Hemming? A Simple Yet Essential Process
Metal hemming technique
Sheet metal hemming is a sheet metal fabrication technique entailing the folding of a metal sheet onto itself. The goal of the technique is mostly to enhance sheet metal aesthetics, strength, and durability.
Hemming results in a double-layered edge, enhancing strength, aesthetics, and safety. The method is popular in industrial settings, from automotive to construction industries.
It is one of the fundamental sheet metal fabrication methods, including punching, stamping, and bending. We compared stamping and punching in punching vs. stamping: key differences & industrial uses and suggest you check the insights offered there.
Learn How to Make a Hem on Sheet Metal?
As mentioned, metal hemming is a step-wise process that culminates in a double-layered edge. Similar to the steps in this article: Sheet Metal Bending: Methods, Materials & Services Explained, the machinist must follow several steps for the best metal hemming results.
Prolean Tech experts follow these steps to deliver the best hemming solutions for users across industries:
Step 1: Edge Preparation for a Clean Surface
The hemming process must start with the preparation of the metal surface. Any dirt or contaminant that can interfere with the process is removed.
Step 2: Pre-hemming to Start
After cleaning the surface of all dirt, the sheet metal is subjected to pre-hemming. This is where the machinist forms the initial bend on the sheet metal. The bend of about 145 degrees creates the initial size of the hem.
Step 3: The Main Hem Formation Step
The preformed bend can now be completed to create the predetermined hem. Depending on the hem type, different tools such as hemming rollers, presses, and CNC machines are used for completion.
Hemming tool
Step 4: Smoothing and Finishing to Complete
With the sheet metal hem now formed, the machinist smoothens and finishes the edge. A machine that applies a balanced force, say a press brake, is used for this process. The purpose of this step is to flatten and refine the hem edge as specified in the design.
Step 5: Quality Control and Precision
Quality control and precision are a central part of the entire process. The metal fabrication process is incomplete if it doesn’t maintain the correct hem gauge.
Apart from helping us meet industry standards, the hem gauge is key to preventing sheet metal cracking. Overall, prioritizing quality control and precision enhances part durability and saves costs.
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What Are The Common Types of Sheet Metal Hemming for You to Consider?
There are different types of hemming, each with pros and cons. Your option should be based on factors such as the type of material and design requirements.
Understanding the different types of hems is crucial to attaining the desired results in your metal fabrication project.
Here are the most common designs:
Closed/crushed Hem for Crackless Materials
A closed hem
In closed or crushed hem, the sheet metal is completely rolled on itself, creating a flush edge sheet metal. This type of hem is ideal for cold-rolled steel, stainless steel, and any other material that doesn’t crack on rolling.
You will mostly find the closed hem in automobile bodies, HVAC enclosures, and appliances. Users like the simplicity of the hem and how smooth it turns out.
Teardrop Hem for Less Elastic Materials
Teardrop hem
As captured in the name, a teardrop hem has a teardrop-like loop. This is because the hem is done beyond the 180-degree mark. Machinists apply the hem in less elastic materials, such as aluminum sheet metal.
Open Hem for Safety and Ease of Assembly
Open hem
An air pocket and a soft curve on the edge characterize the open sheet metal hem. Aluminum, stainless steel, and cold-rolled steel create good open hems.
We use open hems for edges that often come into contact with humans. Examples are in metal covers and cabinets.
Rolled Hem for Aesthetics and Safety
Rolled hemming in sheet metal
In the rolled hem type, the edge assumes a round shape to create a smooth surface. The edge sheet metal is visually appealing, safe, and strong. You can see a lot of this method in car doors, HVAC enclosures, and aircraft fuselage panels.
Want to learn more about the options in hemming so you can choose the best one for your project? Talk to our team today for a deeper discussion of the possibilities.
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Consider the Benefits of Sheet Metal Hemming
Does hemming make sense for my project? There are many benefits to accrue from professional metal hemming services by Prolean Tech.
First, our company deals with as many types of materials as you can imagine. Our lead time is as short as one day, and we have domestic and overseas partners to handle any volume.
Further, we have the most advanced press brakes for metal hemming projects, complementing this with unmatched skills and professionalism.
Let’s outline several benefits of this type of metal edge.
High Aesthetic Value
Sheet metal subjected to quality hemming has smoother, more rounded hemming edges that are easier to finish. The result is a more beautiful and appealing appearance. This element is instrumental in cars and many other products that lay a significant premium on appearance.
Enhanced Structural Integrity
Sheet metal parts are much stronger and structurally functionaluseful with hemming edges. Consider this fact: Folding a sheet metal part doubles its thickness at that point and also increases strength, especially for assembly.
Hemming for stronger structures
The sheet metal can withstand more stress and load at the hemmed edge. Consequently, hemming makes products appealing for applications requiring higher structural resilience.
Improved Corrosion and Wear Resistance
The resulting folded hemming edges of sheet metal are more hidden from elements that cause wear and corrosion. Therefore, sheet metal hemming can minimize corrosion and wear on sheet metal surfaces.
If these are the benefits you have been searching for in sheet metal parts, Prolean Tech uses the best options of the hem tool sheet metal. Call us today to start the transformation of your business.
What are the Common Applications of Sheet Metal Hemming? The Options for You
You can use hemming in many applications, from the automotive industry to structural projects. Prolean Tech is here to make it successful regardless of your industry.
The applicable areas for hemming that we can offer our superior metal hemming services include the following:
Automotive Industry
Edged parts in the automotive industry often incorporate hemming. Talk of hoods, roofs, and doors. Smoothening the edges of these items using this technique shows a difference.
Hemming for car door
Of course, the hem flanges make the cars more visually appealing by nicely connecting the outer and inner planes. Beyond that, sheet hemming adds structural strength and durability to the parts.
Appliance and HVAC Industry
Hemming is preferred to remove sharp edges and form perfect seals in appliances and HVAC products. Smooth edges are crucial for the safety of users and to enhance aesthetics.
Hemmed edges HVAC unit
Construction Industry
In the same way, professionals in the construction industry widely use metal hemming to give their products an appealing and professional look. Sheet metal frames and supports often incorporate these features for multiple functions.
Hemming in sheet metal for roof and gutter system
Aerospace Industry
The aerospace industry is another popular destination for our hemming products.
The technique is used in aircraft sections undergoing tough operating conditions. Examples are doors, interior panels, engine nacelles, and fuselage panels.
A hemmed edge for aircraft
There are so many other applications for sheet metal hemming; we would be excited to discuss the options with you. Inquire now about our sheet metal bending services, and we will jump into action immediately.
The Sheet Metal Hemming Materials You Could Use
It could be confusing with all the material options available, let alone the hem tool sheet metal options. You have several factors to consider when considering any material. We have mentioned some of the materials earlier, but let us review them more closely now.
Stainless Steel for Corrosion and Wear Resistance
Consider stainless steel if you are looking for corrosion and wear-resistant sheet metal hems. The material is highly regarded for durability and strength; it is ideal for hemmings where cracks are undesirable. The only challenge with stainless steel sheets is the difficulty of fabricating them.
You can learn more about the suitability of steel in fabrication projects in this guide: Complete Guide to Steel Sheet Metal Fabrication: Benefits, Types & Applications.
Cold-rolled Steel: Your Bet for Versatility
Choose cold-rolled steel if you want a blend of strength and versatility. Cold-rolled steel is easy to bend at room temperature, a capability that translates to a better surface finish and higher strength. We prefer this material for hemming projects where simplicity and lack of further surface coating are priorities.
This list of materials for hemming edges is not conclusive. We are open to actualizing your project goals using materials, designs, and other strategies.
So, are you now ready to start a partnership with a reputable sheet metal fabrication company? With the tips shared in Your Complete Guide to Finding the Best Online Sheet Metal Fabrication Companies, you will realize why Prolean Tech easily ticks all the boxes.
The Takeaway
The takeaway is that sheet metal hemming is inseparable from sheet metal fabrication projects. The technique produces aesthetically pleasing, stronger, durable sheet metal edges. That’s why it is prominent in aerospace, automotive, and household appliances.
Partner with an established service provider to use the right sheet metal for hemming and apply the best manufacturing technologies.
Undoubtedly, CNC machining emerges as a preferred method for unmatched efficiency and precision for different types of hems.
Are you wary of challenges such as warping, cracks, and thickness inconsistency in the hems? Are you interested in the most versatile sheet metal hemming services? Engage Prolean Tech, Get an Instant Quote, and you will never regret it.
FAQs
What does open hem mean?
An open hem is a type of hemming that does not fold completely but rather leaves a space between the metal layers. Designers prefer this hem type for smoothness and strength.
What thickness is sheet metal hemming?
The thickness of a hemmed edge can vary from less than a mm to several mm. It all depends on the metal, design requirements, and the hemming technique.
What is the difference between hem and seam sheet metal?
The difference is that while a hem forms two layers when metal is folded at the edge, a seam sheet metal connects two pieces. In other words, a hem reinforces the strength and appearance of an edge, while a seam joins two sheets.
What is the rule of thumb for sheet metal?
Sheet metal has a rule of thumb: the sheet thickness should be twice the hem radius to prevent failure.
Is sheet metal hemming expensive?
The cost of hemming can vary significantly based on the hem type, material, complexity of the hem, and the hemming technology used. Generally, hemming for mass production is cost-effective.
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