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Full Welding vs Spot Welding for Metal Carts: Which Is Stronger?
2026-03-09
Welding Processes for Metal Carts (Full Welding vs. Spot Welding: Structural Strength Comparison Test)
Last week, an old customer called me, saying that a batch of metal carts they purchased from a certain platform had cracked welds on the load-bearing wheel brackets after less than three months of use.
The photos sent by the customer were very clear—the welds broke cleanly with smooth fracture surfaces, which is a typical failure mode of spot welding. This is not the first time I have seen such a situation. Having worked in the Tool Cabinet and metal cart industry for 15 years, I have seen too many purchasers who, due to lack of understanding of the differences between welding processes, bought carts that started to shake after being pushed in the warehouse for two months. Today, I won’t talk about empty words. I’ll directly use the comparison test data of full welding vs. spot welding that our laboratory just completed to tell you the real differences between these two processes, helping you spot problems at a glance during your next purchase.
1. Full Welding Process: How Continuous Welds Determine the Real Load Capacity Limit of Carts
As the name suggests, full welding fills the entire joint of metal components with solder to form a continuous whole. During our destructive test last week, a heavy-duty cart using the full welding process first had a deformed bottom plate when the load reached 800 kg, but all weld positions remained intact. This is the value of full welding—the strength of the welds is often higher than that of the base metal itself.
Real Data
In our laboratory, tensile tests were conducted on 3mm thick Q235 steel plate welding samples of the same specification. The average fracture load of full-welded samples was 12.8kN, and all fracture positions occurred on the base metal outside the heat-affected zone. What does this mean? The welds are stronger than the steel plate itself.
Many B2B customers ask: "Is the appearance of full welding not good-looking?" It’s true that full welding requires grinding, but this is precisely the detail to judge whether the supplier is attentive. Last year, a hardware wholesale customer insisted that we make full-welded carts. His end users worked in auto repair shops and pushed carts full of tools on uneven ground every day. When he re-ordered half a year later, he said that the workers below reacted, "This cart won’t fall apart no matter how we push it."
User Question Answer
Will full welding cause the cart to be unstable when pushed due to thermal deformation? This is a good question. It’s true that welding heat can cause deformation, so the key lies in the post-welding correction process. Every full-welded cart in our factory undergoes three corrections: rough correction, fine correction, and re-correction after assembly. This is why carts of the same specification with full welding are 15%-20% heavier than those with spot welding—more solder is filled in the welds, and the structural rigidity is naturally higher.
2. Spot Welding Process: Why Carts That Are Half the Price Often Cut Corners Here
Spot welding is intermittent welding at the overlapping parts of metals, with gaps left between each section of weld. The biggest advantage of this process is high production efficiency—for the same cart, spot welding is about 40% faster than full welding. But what’s the cost? A significant decline in structural strength and fatigue resistance.
Real Case
Last month, we inspected a faulty cart sent by a customer, which used spot welding. It was used in an e-commerce warehouse, working about 8 hours a day. The failure position was the connection between the push handle and the cart body, where all four spot welds were broken. Observing the fracture surface with a microscope, obvious fatigue cracks could be seen—small stresses generated by each push and pull formed stress concentration points at the gaps of spot welds. Over time, the welds gradually cracked from both ends to the middle.
Data Comparison
Our dynamic fatigue test showed that when pushed continuously over a 30-meter bumpy road under a 500 kg load, the welds of the full-welded cart had no changes. However, after 2000 reciprocations, microcracks began to appear on the steel plate at the spot welding gaps of the spot-welded cart, and some solder joints fell off after 4000 reciprocations. This gap in actual use is the difference between a service life of half a year and three years.
User Question Answer
Are all spot welds bad? Not necessarily. Spot welding is suitable for light-load scenarios, such as file carts used in offices, linen carts used in hotels, with a load capacity of less than 100 kg and a flat use environment. The problem is that some suppliers use spot welding on heavy-duty carts and deceive customers by saying "spot welding is sufficient". The identification method is simple: look at the connection between the cart’s bottom plate and the frame. If the welds are intermittent with visible gaps in between, it is spot welding. Then ask: Will the welds crack when fully loaded? How the other party answers can basically judge whether they are a professional supplier.
3.Welding Process Selection Guide: Match the Right Cart According to the Usage Scenario
Based on customer feedback over the years, I have sorted out a simple matching logic to help you quickly judge which welding process to choose during your next purchase.
Scenario 1: Manufacturing Workshops, Auto Repair Shops, Warehousing and Logistics Centers
The characteristics of such scenarios are uneven ground, slopes, and frequent full-load movement. It is recommended to choose the full welding process, especially for key parts such as load-bearing brackets, connection points between push handles and the cart body, and wheel covers. Last year, the full-welded carts we supplied to an auto parts factory were pushed back and forth with molds every day, and there have been no problems for two years.
Real Data
Among our cooperative B2B customers, the after-sales maintenance rate of customers using full-welded carts within three years is 3.2%, while that of spot-welded carts is 17.8%. For wholesalers, this means a huge difference in after-sales costs.
Scenario 2: Offices, Hotels, Light-Load Display Purposes
If you only occasionally push light things and the ground is tiled or wooden, spot-welded carts are completely sufficient. But it is recommended to check one point: the spacing of spot welds should not be too large. According to industry standards, the spot welding spacing should be controlled between 50-80mm, and the length of each solder joint should not be less than 15mm. Some low-priced carts have a spacing of more than 100mm, which is really perfunctory.
User Question Answer
How to quickly judge the welding quality of a cart? Pick up the cart, find a right-angle position, push and pull diagonally, and feel if there is an obvious sense of frame play. Then place the cart on its side, shine a flashlight on the inner side of the welds, and check for defects such as burn-through, pores, and slag inclusions. The welding surface of regular suppliers will be ground smooth, but don’t be deceived by the appearance—no matter how well it is ground, if the solder joints are discontinuous, the strength will not improve.
4.Destructive Test Record: Real Performance of Two Processes on Carts of the Same Specification
To help customers understand the differences more intuitively, we conducted a comparison test. Two carts with exactly the same design specifications, both with a load capacity of 500 kg, one full-welded and one spot-welded, were subjected to destructive loading under the same conditions.
Full-Welded Cart
When loaded to 680 kg, the bottom plate began to deform significantly, but the weld positions remained motionless. When continuing to load to 820 kg, the cart was twisted as a whole, but there was still no weld cracking. The final failure occurred in the side plate buckling instability, and all welds remained intact.
Spot-Welded Cart
When loaded to 450 kg, a slight "clicking" sound was heard, which was the steel plate at the spot welding gap deforming under force. At 580 kg, a solder joint at the root of the push handle suddenly broke, and the entire structure became unstable instantly. When disassembled, it was found that the penetration depth of that solder joint was obviously insufficient. This is another risk of the spot welding process—the quality of solder joints is unstable and greatly affected by the operator’s technical level.
Industry Insight
Why do some manufacturers use spot welding even though they know full welding is better? In addition to cost, there is also production capacity pressure. The training cycle for a skilled welder is at least one year, while spot welding has relatively low skill requirements and is quick to learn. But for factories like us that serve B2B customers, the reorder rate is more important than short-term profits. So we insist on full welding on all heavy-duty carts. Even if the cost is 30% higher, we gain customers who will not be lost for five years.
FAQ: Three Key Welding Questions Purchasers Care Most About
Question 1: Full-welded carts are much more expensive—are they worth it?
It depends on your customer group. If your end users are factories, auto repair shops, warehouses and other high-intensity use scenarios, the failure rate of full-welded carts is about 1/5 that of spot-welded carts. Let’s do the math: a full-welded cart costs 800 yuan and lasts for 5 years, which is 160 yuan a year; a spot-welded cart costs 500 yuan and lasts for 1.5 years, which is 333 yuan a year—not to mention the time and reputation loss caused by after-sales handling. For wholesalers, the customer satisfaction from selling one full-welded cart can bring 3 repeat customers.
Question 2: Is it normal for welds to rust after the cart has been used for a long time?
Because the welding heat treatment changes the surface state of the metal, the weld area is indeed more prone to rust than the base metal, which is a normal phenomenon. But if there is large-area rust within half a year, it indicates two problems: first, insufficient protection during welding, leading to severe oxidation on the weld surface; second, inadequate post-welding treatment, failing to remove welding slag and oxide scale. The standard practice is pickling and passivation or spraying anti-rust primer after welding. Our standard for customers is: no obvious rust in the weld area within two years of normal indoor use.
Question 3: How to restrict welding quality in the purchase contract?
It is recommended that you clearly state two points in the technical terms: first, key force-bearing parts must be fully welded, and the weld height shall not be lower than the thickness of the base metal; second, provide a welding procedure qualification report, including penetration test and mechanical performance test data. Truly powerful suppliers are not afraid of your requirements; they are afraid that you only ask about the price and not the quality. Some European customers we cooperate with even send people to the site to watch the welder’s practical operation exam. Although such customers have strict requirements, once they cooperate, they are very stable.
Meta Description
How to choose the welding process for metal carts? What is the difference in structural strength between full welding and spot welding? Based on real destructive test data, this article compares the load capacity limit, fatigue life and applicable scenarios of the two processes. If you are a purchaser or wholesaler of tool cabinets and metal carts and want to know how to judge product quality from welds, this article can help you avoid purchasing pitfalls and choose a truly durable cart. Click to view detailed test data and selection suggestions.
Keywords
metal cart welding process, difference between full welding and spot welding, cart structural strength test, tool cabinet welding quality, heavy-duty cart purchasing guide, B2B industrial cart supplier, welding process comparison data