The work of the new car-making forces has always been concerned by everyone, because everyone wants to spy on their quality and stability from their work level. Because generally speaking, good workmanship does not necessarily mean good quality stability, but if the workmanship is poor and the product consistency is poor, the quality stability will definitely not be much better.

Then, which of the new forces to build cars has a higher standard of workmanship? How big is the gap between their workmanship and the electric cars produced by traditional big factories? From the control level of their sheet metal cracks, we may get a glimpse of the whole leopard.

I. Measuring tools and data comparison methods

The tool used in this measurement is still the plastic feeler commonly used by the whole vehicle factory to detect the fit clearance. There are four thickness feeler pieces: 0.25mm, 0.5mm, 1mm and 2mm. The dividing value of the feeler gauge is 0.25mm, and the tolerance is 5%, which is enough to meet the precision requirements of rapid measurement, and the plastic material will not scratch the car paint. The measuring method is to combine feeler pieces with different thicknesses and insert them into the joint to measure the minimum and maximum gap values of the joint.

The selected position for this measurement is the joint of four doors and two covers of the vehicle. If there are chrome-plated decorative strips or plastic decorative plates at the joint position, the gap between them is also included in the measurement range, and the manufacturing accuracy and matching accuracy of sheet metal parts and purchased parts are comprehensively considered.

The first is the interval histogram of the measured data of each position, which reflects the fluctuation of the measured values of each position. The shorter the bar, the more uniform the gap at this position. The second is the histogram and normal distribution of all measured data. Histogram indicates the frequency of data, and normal distribution indicates the degree of data concentration. The finer the normal distribution curve, the better the neutrality of the data set, that is, the smaller the difference between the measured values at each position; At the same time, from the X coordinate of the peak value of the normal distribution curve, we can also see the average level of the gap between the four doors and the two covers of this car. The smaller the x value, the smaller the concentrated value of the gap between the four doors and the two covers.

In the final ranking, the degree of data concentration is given priority, that is, the finer the normal distribution curve, the higher the ranking; On the basis of similar data concentration, the smaller the concentration value, the higher the ranking.

Second, compare vehicle selection.

Six cars were selected for this comparison, namely Tesla Model 3, Weilai ES6, Tucki P7, Weimar EX5, Li ONE and BMW iX3. It should be emphasized that this measurement result can only reflect the matching state of the four doors and two covers of Guangzhou Auto Show in 2020, and to some extent, it can reflect the manufacturing technology level of the manufacturer, but it cannot fully represent the batch state (note: the following measurement data units are all in mm).

Third, the comparison results

First of all, let's look at the comparison results directly. From the comparison of normal distribution curves, it can be seen that the consistency of measurement data of BMW iX3 is the best among the six cars, and it is obviously ahead of the new power products. Li ONE's performance was amazing, and Tesla Model 3 was unexpected. The data consistency of the two cars is second only to BMW iX3, and the average gap is smaller than BMW iX3, ranking second and third respectively. Weilai ES6 and Tucki P7 are in the third camp, with a slightly larger gap and poor data consistency. However, according to the previous measurement experience, their performance can also rank in the middle level among traditional luxury brands. Among the six cars, only Weimar EX5 performed poorly, with a big gap between four doors and two covers and poor data consistency.

Fourth, the final ranking of this comparison is:

BMW iX3> Lee ONE> Tesla Model 3> Weilai ES6> Tucki P7> Weimar EX5

1, BMW iX3

The gaps between the four doors and the two cover plates of this BMW iX3 show car are basically 3-4.5mm, and the data consistency is good. The difference between the maximum value and the minimum value of a single seam can basically be controlled within 1mm, and the symmetry of the seam at the same position on the left and right is also good. Only the position data of the left front door has a large deviation, and the gap between the lower plastic plate is obviously larger than that between the door and the fender, but BMW iX3 still has the best matching accuracy between plastic parts and chrome-plated parts among the six cars in the same field. In terms of quality control of external suppliers, BMW is obviously superior to the new force of making cars.

2. Li Yi

The gap between the sheet metal parts of Li ONE is well controlled, especially at the position of the four doors. The gap between the sheet metal parts is basically controlled at about 3cm, and the seams look very uniform and the left-right symmetry is also very good. However, if the connecting parts such as plastic parts, chrome-plated parts and taillights are considered as a whole, the performance of Li ONE is obviously not as good as that of BMW iX3. The biggest gap between the left and right doors is where the lower plastic parts are connected. The gap of chrome trim on the taillight is too large, and the left taillight is not aligned with the middle light bar. Several new forces measured this time all have similar cases of poor matching of purchased parts. In terms of quality control of external suppliers, the new forces have to pay tuition fees again.

3. Tesla Model 3

The Tesla Model 3 show car does make the seams very small and even, and the left-right symmetry is also very good. At the same time, the average gap between the four doors and the two covers of Tesla Model 3 is still the smallest among the six cars. From the data point of view, the domestic Model 3 is not bad in the gap control of four doors and two covers, and the manufacturing accuracy and matching accuracy of sheet metal parts are well controlled. However, the reason why Tesla Model 3 has achieved such results is partly because it is a car, so there is no connected plastic decorative board under the door panel, and the body design is relatively simple, so it is more difficult to control the seam uniformity than other models in the same field.

The subjective impression is the worst of the six cars, very "American", and the workmanship details are also sloppy, such as the burr on the door sealing strip, the dislocation of the rear lighting board and so on.

4. Weilai ES6

Weilai ES6 is a high-end car. From the measured data, the gap values of four doors and two covers of Weilai ES6 are scattered, which proves that the seam consistency is average. Although the left-right symmetry between the door seam and the tail door seam of Weilai ES6 is good, the front hood seam is obviously larger on the right and smaller on the left, the plastic plate seam under the middle seam of the two doors is larger, and the taillight seam is larger. In the future, Weilai will have to pay more attention to these details that can reflect the skill of building cars and enhance the sense of exquisiteness. 5. Tucki P7

Tucki P7 is the only car in this comparison. Like Tesla Model 3, it has no attached plastic decorative panel under the door panel. As can be seen from the data, Tucki P7 controls the front hood and the left door well, but its final performance can only rank fifth. The main reason is that the taillight design is too complicated.

From Tucki P7 train, we can see many similar places. In order to ensure the design, the engineering difficulty is increased or the practicality is sacrificed. Obviously, this car is dominated by designers. To build such a car, the ability of the engineering team and the manufacturing team is very high, and Tucki needs to continue to work hard.

6. Weimar EX5

The main reason for Weimar EX5' s bottom performance is that the joints between plastic parts are too big. The gap between the plastic parts in the middle of the right door panel reaches 10mm, and a finger can be inserted. Moreover, the measurement data at the same position on the left and right have large deviation and poor symmetry, and the matching of plastic parts under the door panel is basically out of control. In the collocation of sheet metal parts, the front middle seam on both sides of the front cover and the door performs well, but the gap in the back seam of the right door is uneven, and there are not many places to recover the score.

Weimar was originally a traditional car company with the deepest background among the new car-making enterprises that had been mass-produced, and the mass production time was earlier. It should have done better in manufacturing and quality control, but at present, its products don't show any outstanding strength in this respect.