总装车间SPS运行方式分析

图1 总装车间平面布置

随着丰田生产方式在汽车行业的引入，总装车间物流的SPS（Set Parts System）配货方式也在中国得到了极大关注，无论是丰田合资、大众合资还是通用合资都在大力推广应用。SPS配货方式就是按每车装配辆份配送货物的方式。本文将重点分析SPS配货方式的优势、适用条件以及如何合理有效地应用。

SPS运行方式

现以总装车间为例，说明SPS运行方式。

图1是年生产单班5000辆整车的总装车间平面布置图。整车装配在一环形线上完成一次内饰、底盘装配和二次内饰装配，全线有26个装配工位（图1中蓝线所示区域）。SPS区域分三块（图1中粉色线所示区域），即仪表板分装零件配货区、底盘零件配货区和一次内饰及二次内饰零件配货区。

总装车间厂房内仅为中小零件的配货区，大件零部件配货、零部件的拆箱、开捆及大件零部件的分装均在另一厂房内，即物流仓库（见图2）。

图2 物流仓库平面布置

1.配货顺序

总装车间的物流系统在信息控制系统指导下，有条不紊地从仓库货架取出所需零件，按SPS配货方式送到指定工位，配货顺序如下：

（1）中央控制室（CCR）根据市场分析及订单情况安排生产计划，并将生产计划的车辆顺序信息向总装车间情报中心传递。

（2）车辆顺序信息传到总装车间情报中心，由情报信息员根据实际工位查找相应信息指示卡。 （3）情报信息员将信息指示卡投递到SPS供应管理板处。

（4）物流配货人员从SPS供给管理板处获取信息选取配货指示票，配货指示票上标有某个车型在某个工程装配零件的种类和数量。

（5）物流人员按照配货指示票到SPS区配货（KITTTING），放在相应的台车上，物流人员将部品放到运输台车上。

（6）配完后放在供给待发区，物流人员将零件供给到生产线的起始位置。（更先进的方式是AGV自动输送至相应工位。

（7）物流人员将空台车返回到零件供给待发区，通过SPS方式配货完成。

2. 物料配送的四个步骤

在图3的SPS物料及信息流程图中我们可以看到，所有的物料都是经过四个步骤完成运送的：接收物料需求信息（图3中①）；按需求信息进行配货（图3中②）；将配货送到装配线的接收端（图3中③）；随装配线完成装配工序（图3中④）。

SPS运行方式的优势

1.上线点减少

一辆份零件被分成有限的几部份，分别在几个上线点与整车随行。上线点的减少意味着在线旁的物流线路变得简单、清晰了。简单的物流线路意味着交叉点的减少、冲突点的降低。

图3 SPS物料及信息流程图

2.线旁物料面积减少

由于整车所需装配的零件均按辆份与车身随行，线旁的物料面积就不需要了。以往由于生产纲领提高所造成的线旁物料面积的矛盾也就不存在了。

3.通道面积可能削减

如果能够整线实现SPS配货方式，SPS配货的上线点均设在线的端部，那么在整线中部工位没有物料需求，通道也就可以削减或取消了。

4.防错功能

装配线上操作工人的工作内容由原来的挑捡零件和装配零件两道工序变为只有装配零件，而且由于所装配零件有明显差异，操作工人不会出现错装；由于每个随行的料架均是按辆份配送的，所以如果装配后料架上有剩余零件，则为漏装，操作工人可及时发现和纠正错误。

5.减轻操作工人的劳动强度

操作工人不需要去线边的料架去取零件。由于料架是随行的，操作工人可以就近取件，减少了操作工人频繁走动所增加的劳动强度。

6.提高了劳动生产率

由于操作工人减少了取件及挑捡零件的用时，减少了每个装配零件所需的工时，使得整线提高节拍成为可能。

SPS运行方式的局限

1.节省面积问题

无庸置疑，在SPS配货方式中，最大限度地节省了装配线旁的物料面积，但是它增加了配货面积，这部分面积是采用传统送货方式时所不需要的。从整个车间角度上看，总面积没有节省反倒是增加了。

以前面所提厂项为例，16000m2的总面积中，装配车间生产面积为4880 m2，物流配货面积为7186 m2，通道面积为2926 m2，其他辅助面积为1008 m2。从上面的数据可以看出物流配货面积约是装配生产面积的1.47倍（不包括通道面积）。

在另两个丰田厂项中，一个厂总装车间装配生产面积约为13600 m2，而物流面积达到24600 m2，装配与物流面积之比约为1 : 1.8；另一个厂总装车间装配生产面积约为41000 m2，而物流面积达61200 m2，装配与物流面积之比约为1 : 1.49。

而我们以往采用送货制生产方式时，设计的装配生产面积与物流面积之比是按1 : （0.6～0.8）考虑的。

物流面积是非生产面积，是不创造价值的面积。物流面积的增加大大地增加了新厂建设投资和生产厂的场地占用成本，实际上最终增加了产品的成本。这与丰田的精益思想是相悖的。

2.防错功能问题

这里的防错功能包括两个方面，一方面是防装错，即防止差异较小的零件装错车；另一方面是防漏装。在同一条生产线上生产的车型，既使是多品种，也都是一个系列的车型，也就是说，在同一条生产线上生产的车型中的大部分零件及总成件都是一样的。为了少量差

异零件的防错装而把所有零件都放在料车上，从成本和操作难度上综合考虑，是否必要，值得我们探究。

3.配送零件质量保证问题

由于配送零件是按辆份送到每个车旁的，也就是说没有备份，当装配过程中出现质量问题（如零件不合格、损坏或遗失）时，由于没有备份零件，没有线旁的物料供给，那么这辆车只能随其他车一起下线，再到返修区进行装配了。这样大大就增加了返修区的工作量，增加了返修面积。

因此，SPS运行方式对入库零件质量要求非常高，要求配送的零件合格率为100％，并且保证在运送过程中，无质量事故。这对于同种零件成批送货相对容易保证，而对于按辆份配送的方式，由于要将结构各异的零件都放在同一配送小车上，保证起来会有一定的困难。

4.提高生产效率问题

这个问题应该从两个方面讨论：

一个方面是零件搬运问题。SPS运行方式造成了零件的“二次搬运”，将零件取出送到配送区，再从配送区取出零件放到随行料架上，比传统的送货方式增加了一次零件配送，是属于丰田生产方式所说的“7种浪费”之一，可见其是影响生产效率的。

另一个方面是人在装配过程中的取件用时问题。SPS运行方式一直强调操作工人从随行料架上取件比线旁取件所走的距离短。事实上，笔者在实行SPS运行方式的总装车间看到的是随行料架放在两工位之间，操作工人到随行料架取件至少要走出1m远，与到线边料架相比并不近。因此，通过随行料架取件和到线旁料架取件对工人装配效率的影响区别是微乎其微的。

5.SPS运行方式适用的零件问题

SPS运行方式是将整车零部件按辆份放在随行料架上，但我们很难想象大型总成件，如保险杠、座椅和轮胎等也放在随行料架上，这些零件会使随行料架变得很大；另外还有一些有分装内容的总成件，如仪表板、车门、动力总成和风挡玻璃等也不会采用随行料架送到装

配工位的。由此可见，SPS运行方式适用的是中小型的零件，如成套锁、门把手和内护板等件。

SPS的适用条件

SPS运行方式最大的优势体现在不同种类车型的差异件的取用和判断上，最大限度地减少了操作工人的判断失误。

SPS运行方式并不适用于大批量的整车生产方式。SPS运行方式更适用的是批量小、品种多且差异件多的整车试制线，或一些零件比较小，而零件在运送过程中不易受到损伤的总成件分装。

Toyota’s New Material-Handling System Shows TPS’s Flexibility

Toyota Motor Corporation has introduced a new material-handling system based on kitting to reduce complexity and improve quality in assembly areas.

The new approach was introduced in Japan and China, according to Art Smalley, author of the Lean Enterprise Institute workbook Creating Level Pull. Smalley saw the new system in action on an engine assembly line during a recent tour of Toyota facilities in Japan. He was one of the first Americans to work for Toyota in Japan in the 1980s and helped transfer Toyota’s equipment and lean manufacturing methods overseas.

A spokesman for Toyota Motor North America said the kitting system was being introduced on “more and more lines” at the Georgetown facility and elsewhere in North America. He said it was “not a complete sea change” in parts presentation and wasn’t applicable to all production areas.

Smalley said the system, called the set pallet system (SPS) in Japan, appeared best suited to automated lines, rather than cells. The new approach removed line-side storage racks, often

called flow racks, so operators no longer walked from their assembly stations to get parts. Instead, electronic signals told material handlers what parts to select from bins separate from the line. They then selected and placed the parts on pallets traveling with the engines being assembled (see diagrams below

“Visually, it’s quite a difference because the flow racks are gone,” said Smalley. “I was surprised. It was a much more open and clear area than the traditional scenario with all the material around the line, which can block you from seeing. The line is so wide open now.”

More Value-Added Work

At Georgetown, the correct parts for a particular Camry or Avalon are selected into a tray that is placed inside the car as it heads down the line. Because part selection is done upstream, assemblers can “focus on the quality of installation,” according to the Toyota spokesman. Variety and the resulting complexity have proliferated as more and more features are offered to customers. For instance, before the new system was introduced for the current generation Camry and Avalon, team members had to choose between 24 varieties of sun visors.

The change means operators now focus nearly 100% of their time on the value-added work of installing parts because they no longer have to perform the nonvalue-adding task of walking a few steps to retrieve parts from flow racks, Smalley noted. “Operators stay in a very tight zone, doing almost 100% value-added time.”

The switch also eliminates reaching, stretching, and searching for parts by assembly operators. The new arrangement also makes training operators and material handlers easier because the job responsibilities are narrower.

The new system concentrates walking and parts selection on the material handlers who are positioned every seven to 10 stations along the engine assembly line, Smalley said. Although the new system increased the number of material handlers, he commented that, on

average, Toyota estimated that the total productivity change was neutral due to the more effective use of direct labor. A minor drawback to the new approach was that it made adding or subtracting pickers incrementally as takt time changed somewhat harder to do.

Advantages and Disadvantages

The big advantage of the new material handling system is simplicity and quality improvement through error avoidance. Smalley explained that Toyota Japan had about 5% seasonal or temporary workers when he was there in the 1980s. “Now the figure is up to 40% in some plants,” he said. “Also the work force is younger than it was 20 years ago and labor law changes allow for more women to work in assembly.”

All these trends create a workforce that is less experienced with factory work and less familiar with automotive components than in the past. Combined with the proliferation of component variety, part selection errors were occurring and small quality problems, like assembly errors and bolts not being sufficiently torqued, were getting downstream. “I guess they just couldn’t poka-yoke everything and the logical step was to simplify further,” he said.

The new system was introduced at a vehicle assembly plant in China co-owned by Toyota that had limited space for storing material at the final assembly the line, Smalley said. A kaizen effort produced the SPS approach. “Other managers saw it and loved the effect it had on clearing up the area around the line,” he said. “The line became less cluttered, easier to see, easier to walk around, and just felt like a much more open work space. One by one the vehicle plants switched over during the past year or two and now the engine assembly lines are doing the same.”

Although the system is considered new, Smalley points out that there was a similar version being used at line number 14 in Toyota’s Kamigo Engine Plant about 20 years ago. The line supplier nearly 100 different types of engines and thousands of minor variations at the part number level used on the engine worldwide. Other lines did not suffer the same complexity

issues and the system thus never spread. Smalley noted that adoption of the SPS material handling system today demonstrates that TPS flexibly adapts to the needs of the situation rather than forcing a solution to maintain standardization.

Operators on the traditional assembly line at Toyota spent non value-adding time walking to flow racks to select parts.

Operator walking is dramatically reduced and parts selection eliminated under the new kitting system, also known as the set pallet system. Walking and selecting is concentrated on material handlers, freeing assembly operators to concentrate on installation. In the diagram, operators walk from position A to B during installation, then back to position A. After receiving an electronic signal on what parts to select, material handlers take the parts from line-side bins to a pallet or tray traveling with the car or engine being assembled. Material handlers bring empty trays back to the racks for replenishment at the end of their station positions.

This representative analysis shows in general how operator value-added time increased dramatically under the new system.