Could you please explain the following two sentences to me?

Hello everyone,

Recently I have read an instruction of a kind of insulated glass inspection equipment.I don’t quite understand two sentences of it.Could you please explain to me the two sentences and give me its corresponding sentence of similar meaning?

Two sentences are respectively
1. Thereto the appropriate employees
either inspect while setting the spacer frame ,or in the case of a spacer frame application robot, they are specially appointed for the quality task .
2. However,the complaints oscillate with or without manual control always at around the same rate of 1%.


The paragraph is as follows:

To keep the costs due to customer complains within this range,employees are deployed for manual quality control within the production process .Thereto the appropriate employees either inspect while setting the spacer frame ,or in the case of a spacer frame application robot, they are specially appointed for the quality task .Only in individual cases does the production run without any inspection –and then at the risk of an increased complaint rate .Interestingly However,the complaints oscillate with or without manual control always at around the same rate of 1% This shows that the quality of manual control quickly reaches its “human” borders and therefore its benefits must be challenged.



Thanks :-)

weiqun

1 In the insepection process, employees ispect while setting it, but when this task is done by robot, employees have to be assigned to do the inspection.

2 The level of complaints is around 1% (could be a little more, could be a little less), and this is the same when controlled manually or not.

Dear Richard,

Thank you very much for your help.You are always the first to help me.

I have one more question here to ask you.What does thereto mean here?and could you please explain to me the sentence structure.That is "thereto ..."

Thank you very much!:-)